v12-0001-Add-deduplication-to-nbtree.patch
text/x-patch
Filename: v12-0001-Add-deduplication-to-nbtree.patch
Type: text/x-patch
Part: 0
Patch
Format: unified
Series: patch v12-0001
| File | + | − |
|---|---|---|
| contrib/amcheck/verify_nbtree.c | 105 | 23 |
| src/backend/access/nbtree/nbtinsert.c | 499 | 17 |
| src/backend/access/nbtree/nbtpage.c | 146 | 2 |
| src/backend/access/nbtree/nbtree.c | 119 | 28 |
| src/backend/access/nbtree/nbtsearch.c | 233 | 14 |
| src/backend/access/nbtree/nbtsort.c | 232 | 11 |
| src/backend/access/nbtree/nbtsplitloc.c | 45 | 2 |
| src/backend/access/nbtree/nbtutils.c | 235 | 29 |
| src/backend/access/nbtree/nbtxlog.c | 226 | 13 |
| src/backend/access/nbtree/README | 75 | 1 |
| src/backend/access/rmgrdesc/nbtdesc.c | 18 | 3 |
| src/include/access/nbtree.h | 241 | 32 |
| src/include/access/nbtxlog.h | 43 | 6 |
| src/tools/valgrind.supp | 21 | 0 |
diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index 05e7d67..399743d 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -924,6 +924,7 @@ bt_target_page_check(BtreeCheckState *state)
size_t tupsize;
BTScanInsert skey;
bool lowersizelimit;
+ ItemPointer scantid;
CHECK_FOR_INTERRUPTS();
@@ -994,29 +995,73 @@ bt_target_page_check(BtreeCheckState *state)
/*
* Readonly callers may optionally verify that non-pivot tuples can
- * each be found by an independent search that starts from the root
+ * each be found by an independent search that starts from the root.
+ * Note that we deliberately don't do individual searches for each
+ * "logical" posting list tuple, since the posting list itself is
+ * validated by other checks.
*/
if (state->rootdescend && P_ISLEAF(topaque) &&
!bt_rootdescend(state, itup))
{
char *itid,
*htid;
+ ItemPointer tid = BTreeTupleGetHeapTID(itup);
itid = psprintf("(%u,%u)", state->targetblock, offset);
htid = psprintf("(%u,%u)",
- ItemPointerGetBlockNumber(&(itup->t_tid)),
- ItemPointerGetOffsetNumber(&(itup->t_tid)));
+ ItemPointerGetBlockNumber(tid),
+ ItemPointerGetOffsetNumber(tid));
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("could not find tuple using search from root page in index \"%s\"",
RelationGetRelationName(state->rel)),
- errdetail_internal("Index tid=%s points to heap tid=%s page lsn=%X/%X.",
+ errdetail_internal("Index tid=%s min heap tid=%s page lsn=%X/%X.",
itid, htid,
(uint32) (state->targetlsn >> 32),
(uint32) state->targetlsn)));
}
+ /*
+ * If tuple is actually a posting list, make sure posting list TIDs
+ * are in order.
+ */
+ if (BTreeTupleIsPosting(itup))
+ {
+ ItemPointerData last;
+ ItemPointer current;
+
+ ItemPointerCopy(BTreeTupleGetHeapTID(itup), &last);
+
+ for (int i = 1; i < BTreeTupleGetNPosting(itup); i++)
+ {
+
+ current = BTreeTupleGetPostingN(itup, i);
+
+ if (ItemPointerCompare(current, &last) <= 0)
+ {
+ char *itid,
+ *htid;
+
+ itid = psprintf("(%u,%u)", state->targetblock, offset);
+ htid = psprintf("(%u,%u)",
+ ItemPointerGetBlockNumberNoCheck(current),
+ ItemPointerGetOffsetNumberNoCheck(current));
+
+ ereport(ERROR,
+ (errcode(ERRCODE_INDEX_CORRUPTED),
+ errmsg("posting list heap TIDs out of order in index \"%s\"",
+ RelationGetRelationName(state->rel)),
+ errdetail_internal("Index tid=%s min heap tid=%s page lsn=%X/%X.",
+ itid, htid,
+ (uint32) (state->targetlsn >> 32),
+ (uint32) state->targetlsn)));
+ }
+
+ ItemPointerCopy(current, &last);
+ }
+ }
+
/* Build insertion scankey for current page offset */
skey = bt_mkscankey_pivotsearch(state->rel, itup);
@@ -1074,12 +1119,33 @@ bt_target_page_check(BtreeCheckState *state)
{
IndexTuple norm;
- norm = bt_normalize_tuple(state, itup);
- bloom_add_element(state->filter, (unsigned char *) norm,
- IndexTupleSize(norm));
- /* Be tidy */
- if (norm != itup)
- pfree(norm);
+ if (BTreeTupleIsPosting(itup))
+ {
+ IndexTuple onetup;
+
+ /* Fingerprint all elements of posting tuple one by one */
+ for (int i = 0; i < BTreeTupleGetNPosting(itup); i++)
+ {
+ onetup = BTreeGetNthTupleOfPosting(itup, i);
+
+ norm = bt_normalize_tuple(state, onetup);
+ bloom_add_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm));
+ /* Be tidy */
+ if (norm != onetup)
+ pfree(norm);
+ pfree(onetup);
+ }
+ }
+ else
+ {
+ norm = bt_normalize_tuple(state, itup);
+ bloom_add_element(state->filter, (unsigned char *) norm,
+ IndexTupleSize(norm));
+ /* Be tidy */
+ if (norm != itup)
+ pfree(norm);
+ }
}
/*
@@ -1087,7 +1153,8 @@ bt_target_page_check(BtreeCheckState *state)
*
* If there is a high key (if this is not the rightmost page on its
* entire level), check that high key actually is upper bound on all
- * page items.
+ * page items. If this is a posting list tuple, we'll need to set
+ * scantid to be highest TID in posting list.
*
* We prefer to check all items against high key rather than checking
* just the last and trusting that the operator class obeys the
@@ -1127,6 +1194,9 @@ bt_target_page_check(BtreeCheckState *state)
* tuple. (See also: "Notes About Data Representation" in the nbtree
* README.)
*/
+ scantid = skey->scantid;
+ if (state->heapkeyspace && !BTreeTupleIsPivot(itup))
+ skey->scantid = BTreeTupleGetMaxTID(itup);
if (!P_RIGHTMOST(topaque) &&
!(P_ISLEAF(topaque) ? invariant_leq_offset(state, skey, P_HIKEY) :
invariant_l_offset(state, skey, P_HIKEY)))
@@ -1150,6 +1220,7 @@ bt_target_page_check(BtreeCheckState *state)
(uint32) (state->targetlsn >> 32),
(uint32) state->targetlsn)));
}
+ skey->scantid = scantid;
/*
* * Item order check *
@@ -1164,11 +1235,13 @@ bt_target_page_check(BtreeCheckState *state)
*htid,
*nitid,
*nhtid;
+ ItemPointer tid;
itid = psprintf("(%u,%u)", state->targetblock, offset);
+ tid = BTreeTupleGetHeapTID(itup);
htid = psprintf("(%u,%u)",
- ItemPointerGetBlockNumberNoCheck(&(itup->t_tid)),
- ItemPointerGetOffsetNumberNoCheck(&(itup->t_tid)));
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
nitid = psprintf("(%u,%u)", state->targetblock,
OffsetNumberNext(offset));
@@ -1177,9 +1250,11 @@ bt_target_page_check(BtreeCheckState *state)
state->target,
OffsetNumberNext(offset));
itup = (IndexTuple) PageGetItem(state->target, itemid);
+
+ tid = BTreeTupleGetHeapTID(itup);
nhtid = psprintf("(%u,%u)",
- ItemPointerGetBlockNumberNoCheck(&(itup->t_tid)),
- ItemPointerGetOffsetNumberNoCheck(&(itup->t_tid)));
+ ItemPointerGetBlockNumberNoCheck(tid),
+ ItemPointerGetOffsetNumberNoCheck(tid));
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
@@ -1189,10 +1264,10 @@ bt_target_page_check(BtreeCheckState *state)
"higher index tid=%s (points to %s tid=%s) "
"page lsn=%X/%X.",
itid,
- P_ISLEAF(topaque) ? "heap" : "index",
+ P_ISLEAF(topaque) ? "min heap" : "index",
htid,
nitid,
- P_ISLEAF(topaque) ? "heap" : "index",
+ P_ISLEAF(topaque) ? "min heap" : "index",
nhtid,
(uint32) (state->targetlsn >> 32),
(uint32) state->targetlsn)));
@@ -1953,10 +2028,10 @@ bt_tuple_present_callback(Relation index, HeapTuple htup, Datum *values,
* verification. In particular, it won't try to normalize opclass-equal
* datums with potentially distinct representations (e.g., btree/numeric_ops
* index datums will not get their display scale normalized-away here).
- * Normalization may need to be expanded to handle more cases in the future,
- * though. For example, it's possible that non-pivot tuples could in the
- * future have alternative logically equivalent representations due to using
- * the INDEX_ALT_TID_MASK bit to implement intelligent deduplication.
+ * Caller does normalization for non-pivot tuples that have a posting list,
+ * since dummy CREATE INDEX callback code generates new tuples with the same
+ * normalized representation. Deduplication is performed opportunistically,
+ * and in general there is no guarantee about how or when it will be applied.
*/
static IndexTuple
bt_normalize_tuple(BtreeCheckState *state, IndexTuple itup)
@@ -2087,6 +2162,7 @@ bt_rootdescend(BtreeCheckState *state, IndexTuple itup)
insertstate.itup = itup;
insertstate.itemsz = MAXALIGN(IndexTupleSize(itup));
insertstate.itup_key = key;
+ insertstate.in_posting_offset = 0;
insertstate.bounds_valid = false;
insertstate.buf = lbuf;
@@ -2094,7 +2170,9 @@ bt_rootdescend(BtreeCheckState *state, IndexTuple itup)
offnum = _bt_binsrch_insert(state->rel, &insertstate);
/* Compare first >= matching item on leaf page, if any */
page = BufferGetPage(lbuf);
+ /* Should match on first heap TID when tuple has a posting list */
if (offnum <= PageGetMaxOffsetNumber(page) &&
+ insertstate.in_posting_offset <= 0 &&
_bt_compare(state->rel, key, page, offnum) == 0)
exists = true;
_bt_relbuf(state->rel, lbuf);
@@ -2560,14 +2638,18 @@ static inline ItemPointer
BTreeTupleGetHeapTIDCareful(BtreeCheckState *state, IndexTuple itup,
bool nonpivot)
{
- ItemPointer result = BTreeTupleGetHeapTID(itup);
+ ItemPointer result;
BlockNumber targetblock = state->targetblock;
- if (result == NULL && nonpivot)
+ /* Shouldn't be called with heapkeyspace index */
+ Assert(state->heapkeyspace);
+ if (BTreeTupleIsPivot(itup) == nonpivot)
ereport(ERROR,
(errcode(ERRCODE_INDEX_CORRUPTED),
errmsg("block %u or its right sibling block or child block in index \"%s\" contains non-pivot tuple that lacks a heap TID",
targetblock, RelationGetRelationName(state->rel))));
+ result = BTreeTupleGetHeapTID(itup);
+
return result;
}
diff --git a/src/backend/access/nbtree/README b/src/backend/access/nbtree/README
index 6db203e..50ec9ef 100644
--- a/src/backend/access/nbtree/README
+++ b/src/backend/access/nbtree/README
@@ -432,7 +432,10 @@ because we allow LP_DEAD to be set with only a share lock (it's exactly
like a hint bit for a heap tuple), but physically removing tuples requires
exclusive lock. In the current code we try to remove LP_DEAD tuples when
we are otherwise faced with having to split a page to do an insertion (and
-hence have exclusive lock on it already).
+hence have exclusive lock on it already). Deduplication can also prevent
+a page split, but removing LP_DEAD tuples is the preferred approach.
+(Note that posting list tuples can only have their LP_DEAD bit set when
+every "logical" tuple represented within the posting list is known dead.)
This leaves the index in a state where it has no entry for a dead tuple
that still exists in the heap. This is not a problem for the current
@@ -710,6 +713,77 @@ the fallback strategy assumes that duplicates are mostly inserted in
ascending heap TID order. The page is split in a way that leaves the left
half of the page mostly full, and the right half of the page mostly empty.
+Notes about deduplication
+-------------------------
+
+We deduplicate non-pivot tuples in non-unique indexes to reduce storage
+overhead, and to avoid or at least delay page splits. Deduplication alters
+the physical representation of tuples without changing the logical contents
+of the index, and without adding overhead to read queries. Non-pivot
+tuples are folded together into a single physical tuple with a posting list
+(a simple array of heap TIDs with the standard item pointer format).
+Deduplication is always applied lazily, at the point where it would
+otherwise be necessary to perform a page split. It occurs only when
+LP_DEAD items have been removed, as our last line of defense against
+splitting a leaf page. We can set the LP_DEAD bit with posting list
+tuples, though only when all table tuples are known dead. (Bitmap scans
+cannot perform LP_DEAD bit setting, and are the common case with indexes
+that contain lots of duplicates, so this downside is considered
+acceptable.)
+
+Large groups of logical duplicates tend to appear together on the same leaf
+page due to the special duplicate logic used when choosing a split point.
+This facilitates lazy/dynamic deduplication. Deduplication can reliably
+deduplicate a large localized group of duplicates before it can span
+multiple leaf pages. Posting list tuples are subject to the same 1/3 of a
+page restriction as any other tuple.
+
+Lazy deduplication allows the page space accounting used during page splits
+to have absolutely minimal special case logic for posting lists. A posting
+list can be thought of as extra payload that suffix truncation will
+reliably truncate away as needed during page splits, just like non-key
+columns from an INCLUDE index tuple. An incoming tuple (which might cause
+a page split) can always be thought of as a non-posting-list tuple that
+must be inserted alongside existing items, without needing to consider
+deduplication. Most of the time, that's what actually happens: incoming
+tuples are either not duplicates, or are duplicates with a heap TID that
+doesn't overlap with any existing posting list tuple (lazy deduplication
+avoids rewriting posting lists repeatedly when heap TIDs are inserted
+slightly out of order by concurrent inserters). When the incoming tuple
+really does overlap with an existing posting list, a posting list split is
+performed. Posting list splits work in a way that more or less preserves
+the illusion that all incoming tuples do not need to be merged with any
+existing posting list tuple.
+
+Posting list splits work by "overriding" the details of the incoming tuple.
+The heap TID of the incoming tuple is altered to make it match the
+rightmost heap TID from the existing/originally overlapping posting list.
+The offset number that the new/incoming tuple is to be inserted at is
+incremented so that it will be inserted to the right of the existing
+posting list. The insertion (or page split) operation that completes the
+insert does one extra step: an in-place update of the posting list. The
+update changes the posting list such that the "true" heap TID from the
+original incoming tuple is now contained in the posting list. We make
+space in the posting list by removing the heap TID that became the new
+item. The size of the posting list won't change, and so the page split
+space accounting does not need to care about posting lists. Also, overall
+space utilization is improved by keeping existing posting lists large.
+
+The representation of posting lists is identical to the posting lists used
+by GIN, so it would be straightforward to apply GIN's varbyte encoding
+compression scheme to individual posting lists. Posting list compression
+would break the assumptions made by posting list splits about page space
+accounting, though, so it's not clear how compression could be integrated
+with nbtree. Besides, posting list compression does not offer a compelling
+trade-off for nbtree, since in general nbtree is optimized for consistent
+performance with many concurrent readers and writers. A major goal of
+nbtree's lazy approach to deduplication is to limit the performance impact
+of deduplication with random updates. Even concurrent append-only inserts
+of the same key value will tend to have inserts of individual index tuples
+in an order that doesn't quite match heap TID order. In general, delaying
+deduplication avoids many unnecessary posting list splits, and minimizes
+page level fragmentation.
+
Notes About Data Representation
-------------------------------
diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index b84bf1c..8fb17d6 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -47,21 +47,26 @@ static void _bt_insertonpg(Relation rel, BTScanInsert itup_key,
BTStack stack,
IndexTuple itup,
OffsetNumber newitemoff,
+ int in_posting_offset,
bool split_only_page);
static Buffer _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf,
Buffer cbuf, OffsetNumber newitemoff, Size newitemsz,
- IndexTuple newitem);
+ IndexTuple newitem, IndexTuple nposting,
+ OffsetNumber in_posting_offset);
static void _bt_insert_parent(Relation rel, Buffer buf, Buffer rbuf,
BTStack stack, bool is_root, bool is_only);
static bool _bt_pgaddtup(Page page, Size itemsize, IndexTuple itup,
OffsetNumber itup_off);
static void _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel);
+static void _bt_dedup_one_page(Relation rel, Buffer buffer, Relation heapRel,
+ Size itemsz);
/*
* _bt_doinsert() -- Handle insertion of a single index tuple in the tree.
*
* This routine is called by the public interface routine, btinsert.
- * By here, itup is filled in, including the TID.
+ * By here, itup is filled in, including the TID. Caller should be
+ * prepared for us to scribble on 'itup'.
*
* If checkUnique is UNIQUE_CHECK_NO or UNIQUE_CHECK_PARTIAL, this
* will allow duplicates. Otherwise (UNIQUE_CHECK_YES or
@@ -123,6 +128,7 @@ _bt_doinsert(Relation rel, IndexTuple itup,
/* PageAddItem will MAXALIGN(), but be consistent */
insertstate.itemsz = MAXALIGN(IndexTupleSize(itup));
insertstate.itup_key = itup_key;
+ insertstate.in_posting_offset = 0;
insertstate.bounds_valid = false;
insertstate.buf = InvalidBuffer;
@@ -300,7 +306,7 @@ top:
newitemoff = _bt_findinsertloc(rel, &insertstate, checkingunique,
stack, heapRel);
_bt_insertonpg(rel, itup_key, insertstate.buf, InvalidBuffer, stack,
- itup, newitemoff, false);
+ itup, newitemoff, insertstate.in_posting_offset, false);
}
else
{
@@ -435,6 +441,7 @@ _bt_check_unique(Relation rel, BTInsertState insertstate, Relation heapRel,
/* okay, we gotta fetch the heap tuple ... */
curitup = (IndexTuple) PageGetItem(page, curitemid);
+ Assert(!BTreeTupleIsPosting(curitup));
htid = curitup->t_tid;
/*
@@ -689,6 +696,7 @@ _bt_findinsertloc(Relation rel,
BTScanInsert itup_key = insertstate->itup_key;
Page page = BufferGetPage(insertstate->buf);
BTPageOpaque lpageop;
+ OffsetNumber location;
lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
@@ -751,13 +759,23 @@ _bt_findinsertloc(Relation rel,
/*
* If the target page is full, see if we can obtain enough space by
- * erasing LP_DEAD items
+ * erasing LP_DEAD items. If that doesn't work out, and if the index
+ * isn't a unique index, try deduplication.
*/
- if (PageGetFreeSpace(page) < insertstate->itemsz &&
- P_HAS_GARBAGE(lpageop))
+ if (PageGetFreeSpace(page) < insertstate->itemsz)
{
- _bt_vacuum_one_page(rel, insertstate->buf, heapRel);
- insertstate->bounds_valid = false;
+ if (P_HAS_GARBAGE(lpageop))
+ {
+ _bt_vacuum_one_page(rel, insertstate->buf, heapRel);
+ insertstate->bounds_valid = false;
+ }
+
+ if (!checkingunique && PageGetFreeSpace(page) < insertstate->itemsz)
+ {
+ _bt_dedup_one_page(rel, insertstate->buf, heapRel,
+ insertstate->itemsz);
+ insertstate->bounds_valid = false; /* paranoia */
+ }
}
}
else
@@ -839,7 +857,31 @@ _bt_findinsertloc(Relation rel,
Assert(P_RIGHTMOST(lpageop) ||
_bt_compare(rel, itup_key, page, P_HIKEY) <= 0);
- return _bt_binsrch_insert(rel, insertstate);
+ location = _bt_binsrch_insert(rel, insertstate);
+
+ /*
+ * Insertion is not prepared for the case where an LP_DEAD posting list
+ * tuple must be split. In the unlikely event that this happens, call
+ * _bt_dedup_one_page() to force it to kill all LP_DEAD items.
+ */
+ if (unlikely(insertstate->in_posting_offset == -1))
+ {
+ _bt_dedup_one_page(rel, insertstate->buf, heapRel, 0);
+ Assert(!P_HAS_GARBAGE(lpageop));
+
+ /* Must reset insertstate ahead of new _bt_binsrch_insert() call */
+ insertstate->bounds_valid = false;
+ insertstate->in_posting_offset = 0;
+ location = _bt_binsrch_insert(rel, insertstate);
+
+ /*
+ * Might still have to split some other posting list now, but that
+ * should never be LP_DEAD
+ */
+ Assert(insertstate->in_posting_offset >= 0);
+ }
+
+ return location;
}
/*
@@ -900,15 +942,65 @@ _bt_stepright(Relation rel, BTInsertState insertstate, BTStack stack)
insertstate->bounds_valid = false;
}
+/*
+ * If the new tuple 'itup' is a duplicate with a heap TID that falls inside
+ * the range of an existing posting list tuple 'oposting', generate new
+ * posting tuple to replace original one and update new tuple so that
+ * it's heap TID contains the rightmost heap TID of original posting tuple.
+ */
+IndexTuple
+_bt_form_newposting(IndexTuple itup, IndexTuple oposting,
+ OffsetNumber in_posting_offset)
+{
+ int nipd;
+ char *replacepos;
+ char *rightpos;
+ Size nbytes;
+ IndexTuple nposting;
+
+ Assert(BTreeTupleIsPosting(oposting));
+ nipd = BTreeTupleGetNPosting(oposting);
+ Assert(in_posting_offset < nipd);
+
+ nposting = CopyIndexTuple(oposting);
+ replacepos = (char *) BTreeTupleGetPostingN(nposting, in_posting_offset);
+ rightpos = replacepos + sizeof(ItemPointerData);
+ nbytes = (nipd - in_posting_offset - 1) * sizeof(ItemPointerData);
+
+ /*
+ * Move item pointers in posting list to make a gap for the new item's
+ * heap TID (shift TIDs one place to the right, losing original
+ * rightmost TID).
+ */
+ memmove(rightpos, replacepos, nbytes);
+
+ /*
+ * Fill the gap with the TID of the new item.
+ */
+ ItemPointerCopy(&itup->t_tid, (ItemPointer) replacepos);
+
+ /*
+ * Copy original (not new original) posting list's last TID into new
+ * item
+ */
+ ItemPointerCopy(BTreeTupleGetPostingN(oposting, nipd - 1), &itup->t_tid);
+ Assert(ItemPointerCompare(BTreeTupleGetMaxTID(nposting),
+ BTreeTupleGetHeapTID(itup)) < 0);
+
+ return nposting;
+}
+
/*----------
* _bt_insertonpg() -- Insert a tuple on a particular page in the index.
*
* This recursive procedure does the following things:
*
+ * + if necessary, splits an existing posting list on page.
+ * This is only needed when 'in_posting_offset' is non-zero.
* + if necessary, splits the target page, using 'itup_key' for
* suffix truncation on leaf pages (caller passes NULL for
* non-leaf pages).
- * + inserts the tuple.
+ * + inserts the new tuple (could be from split posting list).
* + if the page was split, pops the parent stack, and finds the
* right place to insert the new child pointer (by walking
* right using information stored in the parent stack).
@@ -918,7 +1010,8 @@ _bt_stepright(Relation rel, BTInsertState insertstate, BTStack stack)
*
* On entry, we must have the correct buffer in which to do the
* insertion, and the buffer must be pinned and write-locked. On return,
- * we will have dropped both the pin and the lock on the buffer.
+ * we will have dropped both the pin and the lock on the buffer. Caller
+ * should be prepared for us to scribble on 'itup'.
*
* This routine only performs retail tuple insertions. 'itup' should
* always be either a non-highkey leaf item, or a downlink (new high
@@ -936,11 +1029,14 @@ _bt_insertonpg(Relation rel,
BTStack stack,
IndexTuple itup,
OffsetNumber newitemoff,
+ int in_posting_offset,
bool split_only_page)
{
Page page;
BTPageOpaque lpageop;
Size itemsz;
+ IndexTuple nposting = NULL;
+ IndexTuple oposting;
page = BufferGetPage(buf);
lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
@@ -954,6 +1050,8 @@ _bt_insertonpg(Relation rel,
Assert(P_ISLEAF(lpageop) ||
BTreeTupleGetNAtts(itup, rel) <=
IndexRelationGetNumberOfKeyAttributes(rel));
+ /* retail insertions of posting list tuples are disallowed */
+ Assert(!BTreeTupleIsPosting(itup));
/* The caller should've finished any incomplete splits already. */
if (P_INCOMPLETE_SPLIT(lpageop))
@@ -965,6 +1063,42 @@ _bt_insertonpg(Relation rel,
* need to be consistent */
/*
+ * Do we need to split an existing posting list item?
+ */
+ if (in_posting_offset != 0)
+ {
+ ItemId itemid = PageGetItemId(page, newitemoff);
+
+ /*
+ * The new tuple is a duplicate with a heap TID that falls inside the
+ * range of an existing posting list tuple, so split posting list.
+ *
+ * Posting list splits always replace some existing TID in the posting
+ * list with the new item's heap TID (based on a posting list offset
+ * from caller) by removing rightmost heap TID from posting list. The
+ * new item's heap TID is swapped with that rightmost heap TID, almost
+ * as if the tuple inserted never overlapped with a posting list in
+ * the first place. This allows the insertion and page split code to
+ * have minimal special case handling of posting lists.
+ *
+ * The only extra handling required is to overwrite the original
+ * posting list with nposting, which is guaranteed to be the same size
+ * as the original, keeping the page space accounting simple. This
+ * takes place in either the page insert or page split critical
+ * section.
+ */
+ Assert(P_ISLEAF(lpageop));
+ Assert(!ItemIdIsDead(itemid));
+ Assert(in_posting_offset > 0);
+ oposting = (IndexTuple) PageGetItem(page, itemid);
+
+ nposting = _bt_form_newposting(itup, oposting, in_posting_offset);
+
+ /* Alter new item offset, since effective new item changed */
+ newitemoff = OffsetNumberNext(newitemoff);
+ }
+
+ /*
* Do we need to split the page to fit the item on it?
*
* Note: PageGetFreeSpace() subtracts sizeof(ItemIdData) from its result,
@@ -996,7 +1130,8 @@ _bt_insertonpg(Relation rel,
BlockNumberIsValid(RelationGetTargetBlock(rel))));
/* split the buffer into left and right halves */
- rbuf = _bt_split(rel, itup_key, buf, cbuf, newitemoff, itemsz, itup);
+ rbuf = _bt_split(rel, itup_key, buf, cbuf, newitemoff, itemsz, itup,
+ nposting, in_posting_offset);
PredicateLockPageSplit(rel,
BufferGetBlockNumber(buf),
BufferGetBlockNumber(rbuf));
@@ -1075,6 +1210,18 @@ _bt_insertonpg(Relation rel,
elog(PANIC, "failed to add new item to block %u in index \"%s\"",
itup_blkno, RelationGetRelationName(rel));
+ if (nposting)
+ {
+ /*
+ * Handle a posting list split by performing an in-place update of
+ * the existing posting list
+ */
+ Assert(P_ISLEAF(lpageop));
+ Assert(MAXALIGN(IndexTupleSize(oposting)) ==
+ MAXALIGN(IndexTupleSize(nposting)));
+ memcpy(oposting, nposting, MAXALIGN(IndexTupleSize(nposting)));
+ }
+
MarkBufferDirty(buf);
if (BufferIsValid(metabuf))
@@ -1116,6 +1263,7 @@ _bt_insertonpg(Relation rel,
XLogRecPtr recptr;
xlrec.offnum = itup_off;
+ xlrec.in_posting_offset = in_posting_offset;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfBtreeInsert);
@@ -1153,6 +1301,9 @@ _bt_insertonpg(Relation rel,
XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
XLogRegisterBufData(0, (char *) itup, IndexTupleSize(itup));
+ if (nposting)
+ XLogRegisterBufData(0, (char *) nposting,
+ IndexTupleSize(nposting));
recptr = XLogInsert(RM_BTREE_ID, xlinfo);
@@ -1194,6 +1345,10 @@ _bt_insertonpg(Relation rel,
_bt_getrootheight(rel) >= BTREE_FASTPATH_MIN_LEVEL)
RelationSetTargetBlock(rel, cachedBlock);
}
+
+ /* be tidy */
+ if (nposting)
+ pfree(nposting);
}
/*
@@ -1211,10 +1366,16 @@ _bt_insertonpg(Relation rel,
*
* Returns the new right sibling of buf, pinned and write-locked.
* The pin and lock on buf are maintained.
+ *
+ * nposting is a replacement posting for the posting list at the
+ * offset immediately before the new item's offset. This is needed
+ * when caller performed "posting list split", and corresponds to the
+ * same step for retail insertions that don't split the page.
*/
static Buffer
_bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
- OffsetNumber newitemoff, Size newitemsz, IndexTuple newitem)
+ OffsetNumber newitemoff, Size newitemsz, IndexTuple newitem,
+ IndexTuple nposting, OffsetNumber in_posting_offset)
{
Buffer rbuf;
Page origpage;
@@ -1236,6 +1397,7 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
OffsetNumber firstright;
OffsetNumber maxoff;
OffsetNumber i;
+ OffsetNumber replacepostingoff = InvalidOffsetNumber;
bool newitemonleft,
isleaf;
IndexTuple lefthikey;
@@ -1243,6 +1405,13 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
int indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
/*
+ * Determine offset number of posting list that will be updated in place
+ * as part of split that follows a posting list split
+ */
+ if (nposting != NULL)
+ replacepostingoff = OffsetNumberPrev(newitemoff);
+
+ /*
* origpage is the original page to be split. leftpage is a temporary
* buffer that receives the left-sibling data, which will be copied back
* into origpage on success. rightpage is the new page that will receive
@@ -1273,6 +1442,13 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
* newitemoff == firstright. In all other cases it's clear which side of
* the split every tuple goes on from context. newitemonleft is usually
* (but not always) redundant information.
+ *
+ * Note: In theory, the split point choice logic should operate against a
+ * version of the page that already replaced the posting list at offset
+ * replacepostingoff with nposting where applicable. We don't bother with
+ * that, though. Both versions of the posting list must be the same size
+ * and have the same key values, so this omission can't affect the split
+ * point chosen in practice.
*/
firstright = _bt_findsplitloc(rel, origpage, newitemoff, newitemsz,
newitem, &newitemonleft);
@@ -1340,6 +1516,9 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
itemid = PageGetItemId(origpage, firstright);
itemsz = ItemIdGetLength(itemid);
item = (IndexTuple) PageGetItem(origpage, itemid);
+ /* Behave as if origpage posting list has already been swapped */
+ if (firstright == replacepostingoff)
+ item = nposting;
}
/*
@@ -1373,6 +1552,9 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
Assert(lastleftoff >= P_FIRSTDATAKEY(oopaque));
itemid = PageGetItemId(origpage, lastleftoff);
lastleft = (IndexTuple) PageGetItem(origpage, itemid);
+ /* Behave as if origpage posting list has already been swapped */
+ if (lastleftoff == replacepostingoff)
+ lastleft = nposting;
}
Assert(lastleft != item);
@@ -1480,8 +1662,23 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
itemsz = ItemIdGetLength(itemid);
item = (IndexTuple) PageGetItem(origpage, itemid);
+ /*
+ * did caller pass new replacement posting list tuple due to posting
+ * list split?
+ */
+ if (i == replacepostingoff)
+ {
+ /*
+ * swap origpage posting list with post-posting-list-split version
+ * from caller
+ */
+ Assert(isleaf);
+ Assert(itemsz == MAXALIGN(IndexTupleSize(nposting)));
+ item = nposting;
+ }
+
/* does new item belong before this one? */
- if (i == newitemoff)
+ else if (i == newitemoff)
{
if (newitemonleft)
{
@@ -1653,6 +1850,17 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
xlrec.firstright = firstright;
xlrec.newitemoff = newitemoff;
+ /*
+ * If replacing posting item was put on the right page,
+ * we don't need to explicitly WAL log it because it's included
+ * with all the other items on the right page.
+ * Otherwise, save in_posting_offset and newitem to construct
+ * replacing tuple.
+ */
+ xlrec.in_posting_offset = InvalidOffsetNumber;
+ if (replacepostingoff < firstright)
+ xlrec.in_posting_offset = in_posting_offset;
+
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfBtreeSplit);
@@ -1672,8 +1880,11 @@ _bt_split(Relation rel, BTScanInsert itup_key, Buffer buf, Buffer cbuf,
* is not stored if XLogInsert decides it needs a full-page image of
* the left page. We store the offset anyway, though, to support
* archive compression of these records.
+ *
+ * Also save newitem in case posting split was required
+ * to construct new posting.
*/
- if (newitemonleft)
+ if (newitemonleft || xlrec.in_posting_offset)
XLogRegisterBufData(0, (char *) newitem, MAXALIGN(newitemsz));
/* Log the left page's new high key */
@@ -1834,7 +2045,7 @@ _bt_insert_parent(Relation rel,
/* Recursively insert into the parent */
_bt_insertonpg(rel, NULL, pbuf, buf, stack->bts_parent,
- new_item, stack->bts_offset + 1,
+ new_item, stack->bts_offset + 1, 0,
is_only);
/* be tidy */
@@ -2304,6 +2515,277 @@ _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel)
* Note: if we didn't find any LP_DEAD items, then the page's
* BTP_HAS_GARBAGE hint bit is falsely set. We do not bother expending a
* separate write to clear it, however. We will clear it when we split
- * the page.
+ * the page (or when deduplication runs).
+ */
+}
+
+/*
+ * Try to deduplicate items to free some space. If we don't proceed with
+ * deduplication, buffer will contain old state of the page.
+ *
+ * 'itemsz' is the size of the inserter caller's incoming/new tuple, not
+ * including line pointer overhead. This is the amount of space we'll need to
+ * free in order to let caller avoid splitting the page.
+ *
+ * This function should be called after LP_DEAD items were removed by
+ * _bt_vacuum_one_page() to prevent a page split. (It's possible that we'll
+ * have to kill additional LP_DEAD items, but that should be rare.)
+ */
+static void
+_bt_dedup_one_page(Relation rel, Buffer buffer, Relation heapRel, Size itemsz)
+{
+ OffsetNumber offnum,
+ minoff,
+ maxoff;
+ Page page = BufferGetPage(buffer);
+ Page newpage;
+ BTPageOpaque oopaque,
+ nopaque;
+ bool deduplicate = false;
+ BTDedupState *dedupState = NULL;
+ int natts = IndexRelationGetNumberOfAttributes(rel);
+ OffsetNumber deletable[MaxOffsetNumber];
+ int ndeletable = 0;
+
+ /*
+ * Don't use deduplication for indexes with INCLUDEd columns and unique
+ * indexes
+ */
+ deduplicate = (IndexRelationGetNumberOfKeyAttributes(rel) ==
+ IndexRelationGetNumberOfAttributes(rel) &&
+ !rel->rd_index->indisunique);
+ if (!deduplicate)
+ return;
+
+ oopaque = (BTPageOpaque) PageGetSpecialPointer(page);
+ /* init deduplication state needed to build posting tuples */
+ dedupState = (BTDedupState *) palloc0(sizeof(BTDedupState));
+ dedupState->ipd = NULL;
+ dedupState->ntuples = 0;
+ dedupState->itupprev = NULL;
+ dedupState->maxitemsize = BTMaxItemSize(page);
+ dedupState->maxpostingsize = 0;
+
+ minoff = P_FIRSTDATAKEY(oopaque);
+ maxoff = PageGetMaxOffsetNumber(page);
+
+ /*
+ * Delete dead tuples if any. We cannot simply skip them in the cycle
+ * below, because it's necessary to generate special Xlog record
+ * containing such tuples to compute latestRemovedXid on a standby server
+ * later.
+ *
+ * This should not affect performance, since it only can happen in a rare
+ * situation when BTP_HAS_GARBAGE flag was not set and _bt_vacuum_one_page
+ * was not called, or _bt_vacuum_one_page didn't remove all dead items.
+ */
+ for (offnum = minoff;
+ offnum <= maxoff;
+ offnum = OffsetNumberNext(offnum))
+ {
+ ItemId itemid = PageGetItemId(page, offnum);
+
+ if (ItemIdIsDead(itemid))
+ deletable[ndeletable++] = offnum;
+ }
+
+ if (ndeletable > 0)
+ {
+ /*
+ * Skip duplication in rare cases where there were LP_DEAD items
+ * encountered here when that frees sufficient space for caller to
+ * avoid a page split
+ */
+ _bt_delitems_delete(rel, buffer, deletable, ndeletable, heapRel);
+ if (PageGetFreeSpace(page) >= itemsz)
+ {
+ pfree(dedupState);
+ return;
+ }
+
+ /* Continue with deduplication */
+ minoff = P_FIRSTDATAKEY(oopaque);
+ maxoff = PageGetMaxOffsetNumber(page);
+ }
+
+ /*
+ * Scan over all items to see which ones can be deduplicated
+ */
+ newpage = PageGetTempPageCopySpecial(page);
+ nopaque = (BTPageOpaque) PageGetSpecialPointer(newpage);
+
+ /* Make sure that new page won't have garbage flag set */
+ nopaque->btpo_flags &= ~BTP_HAS_GARBAGE;
+
+ /* Copy High Key if any */
+ if (!P_RIGHTMOST(oopaque))
+ {
+ ItemId hitemid = PageGetItemId(page, P_HIKEY);
+ Size hitemsz = ItemIdGetLength(hitemid);
+ IndexTuple hitem = (IndexTuple) PageGetItem(page, hitemid);
+
+ if (PageAddItem(newpage, (Item) hitem, hitemsz, P_HIKEY,
+ false, false) == InvalidOffsetNumber)
+ elog(ERROR, "failed to add highkey during deduplication");
+ }
+
+ /*
+ * Iterate over tuples on the page, try to deduplicate them into posting
+ * lists and insert into new page.
*/
+ for (offnum = minoff;
+ offnum <= maxoff;
+ offnum = OffsetNumberNext(offnum))
+ {
+ ItemId itemid = PageGetItemId(page, offnum);
+ IndexTuple itup = (IndexTuple) PageGetItem(page, itemid);
+
+ Assert(!ItemIdIsDead(itemid));
+
+ if (dedupState->itupprev == NULL)
+ {
+ /* Just set up base/first item in first iteration */
+ Assert(offnum == minoff);
+ dedupState->itupprev = CopyIndexTuple(itup);
+ dedupState->itupprev_off = offnum;
+ continue;
+ }
+
+ if (deduplicate &&
+ _bt_keep_natts_fast(rel, dedupState->itupprev, itup) > natts)
+ {
+ int itup_ntuples;
+ Size projpostingsz;
+
+ /*
+ * Tuples are equal.
+ *
+ * If posting list does not exceed tuple size limit then append
+ * the tuple to the pending posting list. Otherwise, insert it on
+ * page and continue with this tuple as new pending posting list.
+ */
+ itup_ntuples = BTreeTupleIsPosting(itup) ?
+ BTreeTupleGetNPosting(itup) : 1;
+
+ /*
+ * Project size of new posting list that would result from merging
+ * current tup with pending posting list (could just be prev item
+ * that's "pending").
+ *
+ * This accounting looks odd, but it's correct because ...
+ */
+ projpostingsz = MAXALIGN(IndexTupleSize(dedupState->itupprev) +
+ (dedupState->ntuples + itup_ntuples + 1) *
+ sizeof(ItemPointerData));
+
+ if (projpostingsz <= dedupState->maxitemsize)
+ _bt_stash_item_tid(dedupState, itup, offnum);
+ else
+ _bt_dedup_insert(newpage, dedupState);
+ }
+ else
+ {
+ /*
+ * Tuples are not equal, or we're done deduplicating this page.
+ *
+ * Insert pending posting list on page. This could just be a
+ * regular tuple.
+ */
+ _bt_dedup_insert(newpage, dedupState);
+ }
+
+ pfree(dedupState->itupprev);
+ dedupState->itupprev = CopyIndexTuple(itup);
+ dedupState->itupprev_off = offnum;
+
+ Assert(IndexTupleSize(dedupState->itupprev) <= dedupState->maxitemsize);
+ }
+
+ /* Handle the last item */
+ _bt_dedup_insert(newpage, dedupState);
+
+ /*
+ * If no items suitable for deduplication were found, newpage must be
+ * exactly the same as the original page, so just return from function.
+ */
+ if (dedupState->n_intervals == 0)
+ {
+ pfree(dedupState);
+ return;
+ }
+
+ START_CRIT_SECTION();
+
+ PageRestoreTempPage(newpage, page);
+ MarkBufferDirty(buffer);
+
+ /* Log full page write */
+ if (RelationNeedsWAL(rel))
+ {
+ XLogRecPtr recptr;
+ xl_btree_dedup xlrec_dedup;
+
+ xlrec_dedup.n_intervals = dedupState->n_intervals;
+
+ XLogBeginInsert();
+ XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
+ XLogRegisterData((char *) &xlrec_dedup, SizeOfBtreeDedup);
+
+ /* only save non-empthy part of the array */
+ if (dedupState->n_intervals > 0)
+ XLogRegisterData((char *) dedupState->dedup_intervals,
+ dedupState->n_intervals * sizeof(dedupInterval));
+
+ recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_DEDUP_PAGE);
+
+ PageSetLSN(page, recptr);
+ }
+
+ END_CRIT_SECTION();
+
+ /* be tidy */
+ pfree(dedupState);
+}
+
+/*
+ * Add new posting tuple item to the page based on itupprev and saved list of
+ * heap TIDs.
+ */
+void
+_bt_dedup_insert(Page page, BTDedupState *dedupState)
+{
+ IndexTuple to_insert;
+ OffsetNumber offnum = PageGetMaxOffsetNumber(page);
+
+ if (dedupState->ntuples == 0)
+ {
+ /*
+ * Use original itupprev, which may or may not be a posting list
+ * already from some earlier dedup attempt
+ */
+ to_insert = dedupState->itupprev;
+ }
+ else
+ {
+ IndexTuple postingtuple;
+
+ /* form a tuple with a posting list */
+ postingtuple = BTreeFormPostingTuple(dedupState->itupprev,
+ dedupState->ipd,
+ dedupState->ntuples);
+ to_insert = postingtuple;
+ pfree(dedupState->ipd);
+ }
+
+ Assert(IndexTupleSize(dedupState->itupprev) <= dedupState->maxitemsize);
+ /* Add the new item into the page */
+ offnum = OffsetNumberNext(offnum);
+
+ if (PageAddItem(page, (Item) to_insert, IndexTupleSize(to_insert),
+ offnum, false, false) == InvalidOffsetNumber)
+ elog(ERROR, "deduplication failed to add tuple to page");
+
+ if (dedupState->ntuples > 0)
+ pfree(to_insert);
+ dedupState->ntuples = 0;
}
diff --git a/src/backend/access/nbtree/nbtpage.c b/src/backend/access/nbtree/nbtpage.c
index 268f869..5314bbe 100644
--- a/src/backend/access/nbtree/nbtpage.c
+++ b/src/backend/access/nbtree/nbtpage.c
@@ -24,6 +24,7 @@
#include "access/nbtree.h"
#include "access/nbtxlog.h"
+#include "access/tableam.h"
#include "access/transam.h"
#include "access/xlog.h"
#include "access/xloginsert.h"
@@ -42,6 +43,11 @@ static bool _bt_lock_branch_parent(Relation rel, BlockNumber child,
BlockNumber *target, BlockNumber *rightsib);
static void _bt_log_reuse_page(Relation rel, BlockNumber blkno,
TransactionId latestRemovedXid);
+static TransactionId _bt_compute_xid_horizon_for_tuples(Relation rel,
+ Relation heapRel,
+ Buffer buf,
+ OffsetNumber *itemnos,
+ int nitems);
/*
* _bt_initmetapage() -- Fill a page buffer with a correct metapage image
@@ -983,14 +989,52 @@ _bt_page_recyclable(Page page)
void
_bt_delitems_vacuum(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems,
+ OffsetNumber *remainingoffset,
+ IndexTuple *remaining, int nremaining,
BlockNumber lastBlockVacuumed)
{
Page page = BufferGetPage(buf);
BTPageOpaque opaque;
+ Size itemsz;
+ Size remaining_sz = 0;
+ char *remaining_buf = NULL;
+
+ /* XLOG stuff, buffer for remainings */
+ if (nremaining && RelationNeedsWAL(rel))
+ {
+ Size offset = 0;
+
+ for (int i = 0; i < nremaining; i++)
+ remaining_sz += MAXALIGN(IndexTupleSize(remaining[i]));
+
+ remaining_buf = palloc0(remaining_sz);
+ for (int i = 0; i < nremaining; i++)
+ {
+ itemsz = IndexTupleSize(remaining[i]);
+ memcpy(remaining_buf + offset, (char *) remaining[i], itemsz);
+ offset += MAXALIGN(itemsz);
+ }
+ Assert(offset == remaining_sz);
+ }
/* No ereport(ERROR) until changes are logged */
START_CRIT_SECTION();
+ /* Handle posting tuples here */
+ for (int i = 0; i < nremaining; i++)
+ {
+ /* At first, delete the old tuple. */
+ PageIndexTupleDelete(page, remainingoffset[i]);
+
+ itemsz = IndexTupleSize(remaining[i]);
+ itemsz = MAXALIGN(itemsz);
+
+ /* Add tuple with remaining ItemPointers to the page. */
+ if (PageAddItem(page, (Item) remaining[i], itemsz, remainingoffset[i],
+ false, false) == InvalidOffsetNumber)
+ elog(ERROR, "failed to rewrite posting list item in index while doing vacuum");
+ }
+
/* Fix the page */
if (nitems > 0)
PageIndexMultiDelete(page, itemnos, nitems);
@@ -1020,6 +1064,8 @@ _bt_delitems_vacuum(Relation rel, Buffer buf,
xl_btree_vacuum xlrec_vacuum;
xlrec_vacuum.lastBlockVacuumed = lastBlockVacuumed;
+ xlrec_vacuum.nremaining = nremaining;
+ xlrec_vacuum.ndeleted = nitems;
XLogBeginInsert();
XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
@@ -1033,6 +1079,19 @@ _bt_delitems_vacuum(Relation rel, Buffer buf,
if (nitems > 0)
XLogRegisterBufData(0, (char *) itemnos, nitems * sizeof(OffsetNumber));
+ /*
+ * Here we should save offnums and remaining tuples themselves. It's
+ * important to restore them in correct order. At first, we must
+ * handle remaining tuples and only after that other deleted items.
+ */
+ if (nremaining > 0)
+ {
+ Assert(remaining_buf != NULL);
+ XLogRegisterBufData(0, (char *) remainingoffset,
+ nremaining * sizeof(OffsetNumber));
+ XLogRegisterBufData(0, remaining_buf, remaining_sz);
+ }
+
recptr = XLogInsert(RM_BTREE_ID, XLOG_BTREE_VACUUM);
PageSetLSN(page, recptr);
@@ -1042,6 +1101,91 @@ _bt_delitems_vacuum(Relation rel, Buffer buf,
}
/*
+ * Get the latestRemovedXid from the table entries pointed at by the index
+ * tuples being deleted.
+ *
+ * This is a version of index_compute_xid_horizon_for_tuples() specialized to
+ * nbtree, which can handle posting lists.
+ */
+static TransactionId
+_bt_compute_xid_horizon_for_tuples(Relation rel, Relation heapRel,
+ Buffer buf, OffsetNumber *itemnos,
+ int nitems)
+{
+ ItemPointerData *ttids;
+ TransactionId latestRemovedXid = InvalidTransactionId;
+ Page page = BufferGetPage(buf);
+ int arraynitems;
+ int finalnitems;
+
+ /*
+ * Initial size of array can fit everything when it turns out that are no
+ * posting lists
+ */
+ arraynitems = nitems;
+ ttids = (ItemPointerData *) palloc(sizeof(ItemPointerData) * arraynitems);
+
+ finalnitems = 0;
+ /* identify what the index tuples about to be deleted point to */
+ for (int i = 0; i < nitems; i++)
+ {
+ ItemId itemid;
+ IndexTuple itup;
+
+ itemid = PageGetItemId(page, itemnos[i]);
+ itup = (IndexTuple) PageGetItem(page, itemid);
+
+ Assert(ItemIdIsDead(itemid));
+
+ if (!BTreeTupleIsPosting(itup))
+ {
+ /* Make sure that we have space for additional heap TID */
+ if (finalnitems + 1 > arraynitems)
+ {
+ arraynitems = arraynitems * 2;
+ ttids = (ItemPointerData *)
+ repalloc(ttids, sizeof(ItemPointerData) * arraynitems);
+ }
+
+ Assert(ItemPointerIsValid(&itup->t_tid));
+ ItemPointerCopy(&itup->t_tid, &ttids[finalnitems]);
+ finalnitems++;
+ }
+ else
+ {
+ int nposting = BTreeTupleGetNPosting(itup);
+
+ /* Make sure that we have space for additional heap TIDs */
+ if (finalnitems + nposting > arraynitems)
+ {
+ arraynitems = Max(arraynitems * 2, finalnitems + nposting);
+ ttids = (ItemPointerData *)
+ repalloc(ttids, sizeof(ItemPointerData) * arraynitems);
+ }
+
+ for (int j = 0; j < nposting; j++)
+ {
+ ItemPointer htid = BTreeTupleGetPostingN(itup, j);
+
+ Assert(ItemPointerIsValid(htid));
+ ItemPointerCopy(htid, &ttids[finalnitems]);
+ finalnitems++;
+ }
+ }
+ }
+
+ Assert(finalnitems >= nitems);
+
+ /* determine the actual xid horizon */
+ latestRemovedXid =
+ table_compute_xid_horizon_for_tuples(heapRel, ttids, finalnitems);
+
+ pfree(ttids);
+
+ return latestRemovedXid;
+}
+
+/*
* Delete item(s) from a btree page during single-page cleanup.
*
* As above, must only be used on leaf pages.
@@ -1067,8 +1211,8 @@ _bt_delitems_delete(Relation rel, Buffer buf,
if (XLogStandbyInfoActive() && RelationNeedsWAL(rel))
latestRemovedXid =
- index_compute_xid_horizon_for_tuples(rel, heapRel, buf,
- itemnos, nitems);
+ _bt_compute_xid_horizon_for_tuples(rel, heapRel, buf,
+ itemnos, nitems);
/* No ereport(ERROR) until changes are logged */
START_CRIT_SECTION();
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 4cfd528..6759531 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -97,6 +97,8 @@ static void btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
BTCycleId cycleid, TransactionId *oldestBtpoXact);
static void btvacuumpage(BTVacState *vstate, BlockNumber blkno,
BlockNumber orig_blkno);
+static ItemPointer btreevacuumPosting(BTVacState *vstate, IndexTuple itup,
+ int *nremaining);
/*
@@ -263,8 +265,8 @@ btgettuple(IndexScanDesc scan, ScanDirection dir)
*/
if (so->killedItems == NULL)
so->killedItems = (int *)
- palloc(MaxIndexTuplesPerPage * sizeof(int));
- if (so->numKilled < MaxIndexTuplesPerPage)
+ palloc(MaxPostingIndexTuplesPerPage * sizeof(int));
+ if (so->numKilled < MaxPostingIndexTuplesPerPage)
so->killedItems[so->numKilled++] = so->currPos.itemIndex;
}
@@ -1069,7 +1071,8 @@ btvacuumscan(IndexVacuumInfo *info, IndexBulkDeleteResult *stats,
RBM_NORMAL, info->strategy);
LockBufferForCleanup(buf);
_bt_checkpage(rel, buf);
- _bt_delitems_vacuum(rel, buf, NULL, 0, vstate.lastBlockVacuumed);
+ _bt_delitems_vacuum(rel, buf, NULL, 0, NULL, NULL, 0,
+ vstate.lastBlockVacuumed);
_bt_relbuf(rel, buf);
}
@@ -1193,6 +1196,9 @@ restart:
OffsetNumber offnum,
minoff,
maxoff;
+ IndexTuple remaining[MaxOffsetNumber];
+ OffsetNumber remainingoffset[MaxOffsetNumber];
+ int nremaining;
/*
* Trade in the initial read lock for a super-exclusive write lock on
@@ -1229,6 +1235,7 @@ restart:
* callback function.
*/
ndeletable = 0;
+ nremaining = 0;
minoff = P_FIRSTDATAKEY(opaque);
maxoff = PageGetMaxOffsetNumber(page);
if (callback)
@@ -1242,31 +1249,79 @@ restart:
itup = (IndexTuple) PageGetItem(page,
PageGetItemId(page, offnum));
- htup = &(itup->t_tid);
- /*
- * During Hot Standby we currently assume that
- * XLOG_BTREE_VACUUM records do not produce conflicts. That is
- * only true as long as the callback function depends only
- * upon whether the index tuple refers to heap tuples removed
- * in the initial heap scan. When vacuum starts it derives a
- * value of OldestXmin. Backends taking later snapshots could
- * have a RecentGlobalXmin with a later xid than the vacuum's
- * OldestXmin, so it is possible that row versions deleted
- * after OldestXmin could be marked as killed by other
- * backends. The callback function *could* look at the index
- * tuple state in isolation and decide to delete the index
- * tuple, though currently it does not. If it ever did, we
- * would need to reconsider whether XLOG_BTREE_VACUUM records
- * should cause conflicts. If they did cause conflicts they
- * would be fairly harsh conflicts, since we haven't yet
- * worked out a way to pass a useful value for
- * latestRemovedXid on the XLOG_BTREE_VACUUM records. This
- * applies to *any* type of index that marks index tuples as
- * killed.
- */
- if (callback(htup, callback_state))
- deletable[ndeletable++] = offnum;
+ if (BTreeTupleIsPosting(itup))
+ {
+ int nnewipd = 0;
+ ItemPointer newipd = NULL;
+
+ newipd = btreevacuumPosting(vstate, itup, &nnewipd);
+
+ if (nnewipd == 0)
+ {
+ /*
+ * All TIDs from posting list must be deleted, we can
+ * delete whole tuple in a regular way.
+ */
+ deletable[ndeletable++] = offnum;
+ }
+ else if (nnewipd == BTreeTupleGetNPosting(itup))
+ {
+ /*
+ * All TIDs from posting tuple must remain. Do
+ * nothing, just cleanup.
+ */
+ pfree(newipd);
+ }
+ else if (nnewipd < BTreeTupleGetNPosting(itup))
+ {
+ /* Some TIDs from posting tuple must remain. */
+ Assert(nnewipd > 0);
+ Assert(newipd != NULL);
+
+ /*
+ * Form new tuple that contains only remaining TIDs.
+ * Remember this tuple and the offset of the old tuple
+ * to update it in place.
+ */
+ remainingoffset[nremaining] = offnum;
+ remaining[nremaining] =
+ BTreeFormPostingTuple(itup, newipd, nnewipd);
+ nremaining++;
+ pfree(newipd);
+
+ Assert(IndexTupleSize(itup) <= BTMaxItemSize(page));
+ }
+ }
+ else
+ {
+ htup = &(itup->t_tid);
+
+ /*
+ * During Hot Standby we currently assume that
+ * XLOG_BTREE_VACUUM records do not produce conflicts.
+ * That is only true as long as the callback function
+ * depends only upon whether the index tuple refers to
+ * heap tuples removed in the initial heap scan. When
+ * vacuum starts it derives a value of OldestXmin.
+ * Backends taking later snapshots could have a
+ * RecentGlobalXmin with a later xid than the vacuum's
+ * OldestXmin, so it is possible that row versions deleted
+ * after OldestXmin could be marked as killed by other
+ * backends. The callback function *could* look at the
+ * index tuple state in isolation and decide to delete the
+ * index tuple, though currently it does not. If it ever
+ * did, we would need to reconsider whether
+ * XLOG_BTREE_VACUUM records should cause conflicts. If
+ * they did cause conflicts they would be fairly harsh
+ * conflicts, since we haven't yet worked out a way to
+ * pass a useful value for latestRemovedXid on the
+ * XLOG_BTREE_VACUUM records. This applies to *any* type
+ * of index that marks index tuples as killed.
+ */
+ if (callback(htup, callback_state))
+ deletable[ndeletable++] = offnum;
+ }
}
}
@@ -1274,7 +1329,7 @@ restart:
* Apply any needed deletes. We issue just one _bt_delitems_vacuum()
* call per page, so as to minimize WAL traffic.
*/
- if (ndeletable > 0)
+ if (ndeletable > 0 || nremaining > 0)
{
/*
* Notice that the issued XLOG_BTREE_VACUUM WAL record includes
@@ -1291,6 +1346,7 @@ restart:
* that.
*/
_bt_delitems_vacuum(rel, buf, deletable, ndeletable,
+ remainingoffset, remaining, nremaining,
vstate->lastBlockVacuumed);
/*
@@ -1376,6 +1432,41 @@ restart:
}
/*
+ * btreevacuumPosting() -- vacuums a posting tuple.
+ *
+ * Returns new palloc'd posting list with remaining items.
+ * Posting list size is returned via nremaining.
+ *
+ * If all items are dead,
+ * nremaining is 0 and resulting posting list is NULL.
+ */
+static ItemPointer
+btreevacuumPosting(BTVacState *vstate, IndexTuple itup, int *nremaining)
+{
+ int remaining = 0;
+ int nitem = BTreeTupleGetNPosting(itup);
+ ItemPointer tmpitems = NULL,
+ items = BTreeTupleGetPosting(itup);
+
+ /*
+ * Check each tuple in the posting list, save alive tuples into tmpitems
+ */
+ for (int i = 0; i < nitem; i++)
+ {
+ if (vstate->callback(items + i, vstate->callback_state))
+ continue;
+
+ if (tmpitems == NULL)
+ tmpitems = palloc(sizeof(ItemPointerData) * nitem);
+
+ tmpitems[remaining++] = items[i];
+ }
+
+ *nremaining = remaining;
+ return tmpitems;
+}
+
+/*
* btcanreturn() -- Check whether btree indexes support index-only scans.
*
* btrees always do, so this is trivial.
diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index 8e51246..c78c8e6 100644
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -26,10 +26,18 @@
static void _bt_drop_lock_and_maybe_pin(IndexScanDesc scan, BTScanPos sp);
static OffsetNumber _bt_binsrch(Relation rel, BTScanInsert key, Buffer buf);
+static int _bt_binsrch_posting(BTScanInsert key, Page page,
+ OffsetNumber offnum);
static bool _bt_readpage(IndexScanDesc scan, ScanDirection dir,
OffsetNumber offnum);
static void _bt_saveitem(BTScanOpaque so, int itemIndex,
OffsetNumber offnum, IndexTuple itup);
+static void _bt_setuppostingitems(BTScanOpaque so, int itemIndex,
+ OffsetNumber offnum, ItemPointer iptr,
+ IndexTuple itup);
+static inline void _bt_savepostingitem(BTScanOpaque so, int itemIndex,
+ OffsetNumber offnum, ItemPointer iptr,
+ IndexTuple itup);
static bool _bt_steppage(IndexScanDesc scan, ScanDirection dir);
static bool _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir);
static bool _bt_parallel_readpage(IndexScanDesc scan, BlockNumber blkno,
@@ -434,7 +442,10 @@ _bt_binsrch(Relation rel,
* low) makes bounds invalid.
*
* Caller is responsible for invalidating bounds when it modifies the page
- * before calling here a second time.
+ * before calling here a second time, and for dealing with posting list
+ * tuple matches (callers can use insertstate's in_posting_offset field to
+ * determine which existing heap TID will need to be replaced by their
+ * scantid/new heap TID).
*/
OffsetNumber
_bt_binsrch_insert(Relation rel, BTInsertState insertstate)
@@ -453,6 +464,7 @@ _bt_binsrch_insert(Relation rel, BTInsertState insertstate)
Assert(P_ISLEAF(opaque));
Assert(!key->nextkey);
+ Assert(insertstate->in_posting_offset == 0);
if (!insertstate->bounds_valid)
{
@@ -509,6 +521,17 @@ _bt_binsrch_insert(Relation rel, BTInsertState insertstate)
if (result != 0)
stricthigh = high;
}
+
+ /*
+ * If tuple at offset located by binary search is a posting list whose
+ * TID range overlaps with caller's scantid, perform posting list
+ * binary search to set in_posting_offset for caller. Caller must
+ * split the posting list when in_posting_offset is set. This should
+ * happen infrequently.
+ */
+ if (unlikely(result == 0 && key->scantid != NULL))
+ insertstate->in_posting_offset =
+ _bt_binsrch_posting(key, page, mid);
}
/*
@@ -529,6 +552,68 @@ _bt_binsrch_insert(Relation rel, BTInsertState insertstate)
}
/*----------
+ * _bt_binsrch_posting() -- posting list binary search.
+ *
+ * Returns offset into posting list where caller's scantid belongs.
+ *----------
+ */
+static int
+_bt_binsrch_posting(BTScanInsert key, Page page, OffsetNumber offnum)
+{
+ IndexTuple itup;
+ ItemId itemid;
+ int low,
+ high,
+ mid,
+ res;
+
+ /*
+ * If this isn't a posting tuple, then the index must be corrupt (if it is
+ * an ordinary non-pivot tuple then there must be an existing tuple with a
+ * heap TID that equals inserter's new heap TID/scantid). Defensively
+ * check that tuple is a posting list tuple whose posting list range
+ * includes caller's scantid.
+ *
+ * (This is also needed because contrib/amcheck's rootdescend option needs
+ * to be able to relocate a non-pivot tuple using _bt_binsrch_insert().)
+ */
+ Assert(P_ISLEAF((BTPageOpaque) PageGetSpecialPointer(page)));
+ Assert(!key->nextkey);
+ Assert(key->scantid != NULL);
+ itemid = PageGetItemId(page, offnum);
+ itup = (IndexTuple) PageGetItem(page, itemid);
+ if (!BTreeTupleIsPosting(itup))
+ return 0;
+
+ /*
+ * In the unlikely event that posting list tuple has LP_DEAD bit set,
+ * signal to caller that it should kill the item and restart its binary
+ * search.
+ */
+ if (ItemIdIsDead(itemid))
+ return -1;
+
+ /* "high" is past end of posting list for loop invariant */
+ low = 0;
+ high = BTreeTupleGetNPosting(itup);
+ Assert(high >= 2);
+
+ while (high > low)
+ {
+ mid = low + ((high - low) / 2);
+ res = ItemPointerCompare(key->scantid,
+ BTreeTupleGetPostingN(itup, mid));
+
+ if (res >= 1)
+ low = mid + 1;
+ else
+ high = mid;
+ }
+
+ return low;
+}
+
+/*----------
* _bt_compare() -- Compare insertion-type scankey to tuple on a page.
*
* page/offnum: location of btree item to be compared to.
@@ -537,9 +622,18 @@ _bt_binsrch_insert(Relation rel, BTInsertState insertstate)
* <0 if scankey < tuple at offnum;
* 0 if scankey == tuple at offnum;
* >0 if scankey > tuple at offnum.
- * NULLs in the keys are treated as sortable values. Therefore
- * "equality" does not necessarily mean that the item should be
- * returned to the caller as a matching key!
+ *
+ * NULLs in the keys are treated as sortable values. Therefore
+ * "equality" does not necessarily mean that the item should be returned
+ * to the caller as a matching key. Similarly, an insertion scankey
+ * with its scantid set is treated as equal to a posting tuple whose TID
+ * range overlaps with their scantid. There generally won't be a
+ * matching TID in the posting tuple, which caller must handle
+ * themselves (e.g., by splitting the posting list tuple).
+ *
+ * It is generally guaranteed that any possible scankey with scantid set
+ * will have zero or one tuples in the index that are considered equal
+ * here.
*
* CRUCIAL NOTE: on a non-leaf page, the first data key is assumed to be
* "minus infinity": this routine will always claim it is less than the
@@ -563,6 +657,7 @@ _bt_compare(Relation rel,
ScanKey scankey;
int ncmpkey;
int ntupatts;
+ int32 result;
Assert(_bt_check_natts(rel, key->heapkeyspace, page, offnum));
Assert(key->keysz <= IndexRelationGetNumberOfKeyAttributes(rel));
@@ -597,7 +692,6 @@ _bt_compare(Relation rel,
{
Datum datum;
bool isNull;
- int32 result;
datum = index_getattr(itup, scankey->sk_attno, itupdesc, &isNull);
@@ -713,8 +807,24 @@ _bt_compare(Relation rel,
if (heapTid == NULL)
return 1;
+ /*
+ * scankey must be treated as equal to a posting list tuple if its scantid
+ * value falls within the range of the posting list. In all other cases
+ * there can only be a single heap TID value, which is compared directly
+ * as a simple scalar value.
+ */
Assert(ntupatts >= IndexRelationGetNumberOfKeyAttributes(rel));
- return ItemPointerCompare(key->scantid, heapTid);
+ result = ItemPointerCompare(key->scantid, heapTid);
+ if (!BTreeTupleIsPosting(itup) || result <= 0)
+ return result;
+ else
+ {
+ result = ItemPointerCompare(key->scantid, BTreeTupleGetMaxTID(itup));
+ if (result > 0)
+ return 1;
+ }
+
+ return 0;
}
/*
@@ -1451,6 +1561,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
/* initialize tuple workspace to empty */
so->currPos.nextTupleOffset = 0;
+ so->currPos.postingTupleOffset = 0;
/*
* Now that the current page has been made consistent, the macro should be
@@ -1485,8 +1596,30 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
if (_bt_checkkeys(scan, itup, indnatts, dir, &continuescan))
{
/* tuple passes all scan key conditions, so remember it */
- _bt_saveitem(so, itemIndex, offnum, itup);
- itemIndex++;
+ if (!BTreeTupleIsPosting(itup))
+ {
+ _bt_saveitem(so, itemIndex, offnum, itup);
+ itemIndex++;
+ }
+ else
+ {
+ /*
+ * Setup state to return posting list, and save first
+ * "logical" tuple
+ */
+ _bt_setuppostingitems(so, itemIndex, offnum,
+ BTreeTupleGetPostingN(itup, 0),
+ itup);
+ itemIndex++;
+ /* Save additional posting list "logical" tuples */
+ for (int i = 1; i < BTreeTupleGetNPosting(itup); i++)
+ {
+ _bt_savepostingitem(so, itemIndex, offnum,
+ BTreeTupleGetPostingN(itup, i),
+ itup);
+ itemIndex++;
+ }
+ }
}
/* When !continuescan, there can't be any more matches, so stop */
if (!continuescan)
@@ -1519,7 +1652,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
if (!continuescan)
so->currPos.moreRight = false;
- Assert(itemIndex <= MaxIndexTuplesPerPage);
+ Assert(itemIndex <= MaxPostingIndexTuplesPerPage);
so->currPos.firstItem = 0;
so->currPos.lastItem = itemIndex - 1;
so->currPos.itemIndex = 0;
@@ -1527,7 +1660,7 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
else
{
/* load items[] in descending order */
- itemIndex = MaxIndexTuplesPerPage;
+ itemIndex = MaxPostingIndexTuplesPerPage;
offnum = Min(offnum, maxoff);
@@ -1569,8 +1702,37 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
if (passes_quals && tuple_alive)
{
/* tuple passes all scan key conditions, so remember it */
- itemIndex--;
- _bt_saveitem(so, itemIndex, offnum, itup);
+ if (!BTreeTupleIsPosting(itup))
+ {
+ itemIndex--;
+ _bt_saveitem(so, itemIndex, offnum, itup);
+ }
+ else
+ {
+ int i = BTreeTupleGetNPosting(itup) - 1;
+
+ /*
+ * Setup state to return posting list, and save last
+ * "logical" tuple from posting list (since it's the first
+ * that will be returned to scan).
+ */
+ itemIndex--;
+ _bt_setuppostingitems(so, itemIndex, offnum,
+ BTreeTupleGetPostingN(itup, i--),
+ itup);
+
+ /*
+ * Return posting list "logical" tuples -- do this in
+ * descending order, to match overall scan order
+ */
+ for (; i >= 0; i--)
+ {
+ itemIndex--;
+ _bt_savepostingitem(so, itemIndex, offnum,
+ BTreeTupleGetPostingN(itup, i),
+ itup);
+ }
+ }
}
if (!continuescan)
{
@@ -1584,8 +1746,8 @@ _bt_readpage(IndexScanDesc scan, ScanDirection dir, OffsetNumber offnum)
Assert(itemIndex >= 0);
so->currPos.firstItem = itemIndex;
- so->currPos.lastItem = MaxIndexTuplesPerPage - 1;
- so->currPos.itemIndex = MaxIndexTuplesPerPage - 1;
+ so->currPos.lastItem = MaxPostingIndexTuplesPerPage - 1;
+ so->currPos.itemIndex = MaxPostingIndexTuplesPerPage - 1;
}
return (so->currPos.firstItem <= so->currPos.lastItem);
@@ -1598,6 +1760,8 @@ _bt_saveitem(BTScanOpaque so, int itemIndex,
{
BTScanPosItem *currItem = &so->currPos.items[itemIndex];
+ Assert(!BTreeTupleIsPosting(itup));
+
currItem->heapTid = itup->t_tid;
currItem->indexOffset = offnum;
if (so->currTuples)
@@ -1611,6 +1775,61 @@ _bt_saveitem(BTScanOpaque so, int itemIndex,
}
/*
+ * Setup state to save posting items from a single posting list tuple. Saves
+ * the logical tuple that will be returned to scan first in passing.
+ *
+ * Saves an index item into so->currPos.items[itemIndex] for logical tuple
+ * that is returned to scan first. Second or subsequent heap TID for posting
+ * list should be saved by calling _bt_savepostingitem().
+ */
+static void
+_bt_setuppostingitems(BTScanOpaque so, int itemIndex, OffsetNumber offnum,
+ ItemPointer iptr, IndexTuple itup)
+{
+ BTScanPosItem *currItem = &so->currPos.items[itemIndex];
+
+ currItem->heapTid = *iptr;
+ currItem->indexOffset = offnum;
+
+ if (so->currTuples)
+ {
+ /* Save a truncated version of the IndexTuple */
+ Size itupsz = BTreeTupleGetPostingOffset(itup);
+
+ itupsz = MAXALIGN(itupsz);
+ currItem->tupleOffset = so->currPos.nextTupleOffset;
+ memcpy(so->currTuples + so->currPos.nextTupleOffset, itup, itupsz);
+ so->currPos.nextTupleOffset += itupsz;
+ so->currPos.postingTupleOffset = currItem->tupleOffset;
+ }
+}
+
+/*
+ * Save an index item into so->currPos.items[itemIndex] for posting tuple.
+ *
+ * Assumes that _bt_setuppostingitems() has already been called for current
+ * posting list tuple.
+ */
+static inline void
+_bt_savepostingitem(BTScanOpaque so, int itemIndex, OffsetNumber offnum,
+ ItemPointer iptr, IndexTuple itup)
+{
+ BTScanPosItem *currItem = &so->currPos.items[itemIndex];
+
+ currItem->heapTid = *iptr;
+ currItem->indexOffset = offnum;
+
+ if (so->currTuples)
+ {
+ /*
+ * Have index-only scans return the same truncated IndexTuple for
+ * every logical tuple that originates from the same posting list
+ */
+ currItem->tupleOffset = so->currPos.postingTupleOffset;
+ }
+}
+
+/*
* _bt_steppage() -- Step to next page containing valid data for scan
*
* On entry, if so->currPos.buf is valid the buffer is pinned but not locked;
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c
index ab19692..4198770 100644
--- a/src/backend/access/nbtree/nbtsort.c
+++ b/src/backend/access/nbtree/nbtsort.c
@@ -288,6 +288,8 @@ static void _bt_sortaddtup(Page page, Size itemsize,
static void _bt_buildadd(BTWriteState *wstate, BTPageState *state,
IndexTuple itup);
static void _bt_uppershutdown(BTWriteState *wstate, BTPageState *state);
+static void _bt_buildadd_posting(BTWriteState *wstate, BTPageState *state,
+ BTDedupState *dedupState);
static void _bt_load(BTWriteState *wstate,
BTSpool *btspool, BTSpool *btspool2);
static void _bt_begin_parallel(BTBuildState *buildstate, bool isconcurrent,
@@ -830,6 +832,8 @@ _bt_sortaddtup(Page page,
* the high key is to be truncated, offset 1 is deleted, and we insert
* the truncated high key at offset 1.
*
+ * Note that itup may be a posting list tuple.
+ *
* 'last' pointer indicates the last offset added to the page.
*----------
*/
@@ -963,6 +967,11 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
* Overwrite the old item with new truncated high key directly.
* oitup is already located at the physical beginning of tuple
* space, so this should directly reuse the existing tuple space.
+ *
+ * If lastleft tuple was a posting tuple, we'll truncate its
+ * posting list in _bt_truncate as well. Note that it is also
+ * applicable only to leaf pages, since internal pages never
+ * contain posting tuples.
*/
ii = PageGetItemId(opage, OffsetNumberPrev(last_off));
lastleft = (IndexTuple) PageGetItem(opage, ii);
@@ -1002,6 +1011,7 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
* the minimum key for the new page.
*/
state->btps_minkey = CopyIndexTuple(oitup);
+ Assert(BTreeTupleIsPivot(state->btps_minkey));
/*
* Set the sibling links for both pages.
@@ -1043,6 +1053,7 @@ _bt_buildadd(BTWriteState *wstate, BTPageState *state, IndexTuple itup)
Assert(state->btps_minkey == NULL);
state->btps_minkey = CopyIndexTuple(itup);
/* _bt_sortaddtup() will perform full truncation later */
+ BTreeTupleClearBtIsPosting(state->btps_minkey);
BTreeTupleSetNAtts(state->btps_minkey, 0);
}
@@ -1128,6 +1139,136 @@ _bt_uppershutdown(BTWriteState *wstate, BTPageState *state)
}
/*
+ * Add new tuple (posting or non-posting) to the page while building index.
+ */
+static void
+_bt_buildadd_posting(BTWriteState *wstate, BTPageState *state,
+ BTDedupState *dedupState)
+{
+ IndexTuple to_insert;
+
+ /* Return, if there is no tuple to insert */
+ if (state == NULL)
+ return;
+
+ if (dedupState->ntuples == 0)
+ to_insert = dedupState->itupprev;
+ else
+ {
+ IndexTuple postingtuple;
+
+ /* form a tuple with a posting list */
+ postingtuple = BTreeFormPostingTuple(dedupState->itupprev,
+ dedupState->ipd,
+ dedupState->ntuples);
+ to_insert = postingtuple;
+ pfree(dedupState->ipd);
+ }
+
+ _bt_buildadd(wstate, state, to_insert);
+
+ if (dedupState->ntuples > 0)
+ pfree(to_insert);
+ dedupState->ntuples = 0;
+}
+
+/*
+ * Save item pointer(s) of itup to the posting list in dedupState.
+ *
+ * 'itup' is current tuple on page, which comes immediately after equal
+ * 'itupprev' tuple stashed in dedup state at the point we're called.
+ *
+ * Helper function for _bt_load() and _bt_dedup_one_page(), called when it
+ * becomes clear that pending itupprev item will be part of a new/pending
+ * posting list, or when a pending/new posting list will contain a new heap
+ * TID from itup.
+ *
+ * Note: caller is responsible for the BTMaxItemSize() check.
+ */
+void
+_bt_stash_item_tid(BTDedupState *dedupState, IndexTuple itup,
+ OffsetNumber itup_offnum)
+{
+ int nposting = 0;
+
+ if (dedupState->ntuples == 0)
+ {
+ dedupState->ipd = palloc0(dedupState->maxitemsize);
+
+ /*
+ * itupprev hasn't had its posting list TIDs copied into ipd yet (must
+ * have been first on page and/or in new posting list?). Do so now.
+ *
+ * This is delayed because it wasn't initially clear whether or not
+ * itupprev would be merged with the next tuple, or stay as-is. By
+ * now caller compared it against itup and found that it was equal, so
+ * we can go ahead and add its TIDs.
+ */
+ if (!BTreeTupleIsPosting(dedupState->itupprev))
+ {
+ memcpy(dedupState->ipd, dedupState->itupprev,
+ sizeof(ItemPointerData));
+ dedupState->ntuples++;
+ }
+ else
+ {
+ /* if itupprev is posting, add all its TIDs to the posting list */
+ nposting = BTreeTupleGetNPosting(dedupState->itupprev);
+ memcpy(dedupState->ipd,
+ BTreeTupleGetPosting(dedupState->itupprev),
+ sizeof(ItemPointerData) * nposting);
+ dedupState->ntuples += nposting;
+ }
+
+ /* Save info about deduplicated items for future xlog record */
+ dedupState->n_intervals++;
+ /* Save offnum of the first item belongin to the group */
+ dedupState->dedup_intervals[dedupState->n_intervals - 1].from = dedupState->itupprev_off;
+ /*
+ * Update the number of deduplicated items, belonging to this group.
+ * Count each item just once, no matter if it was posting tuple or not
+ */
+ dedupState->dedup_intervals[dedupState->n_intervals - 1].ntups++;
+ }
+
+ /*
+ * Add current tup to ipd for pending posting list for new version of
+ * page.
+ */
+ if (!BTreeTupleIsPosting(itup))
+ {
+ memcpy(dedupState->ipd + dedupState->ntuples, itup,
+ sizeof(ItemPointerData));
+ dedupState->ntuples++;
+ }
+ else
+ {
+ /*
+ * if tuple is posting, add all its TIDs to the pending list that will
+ * become new posting list later on
+ */
+ nposting = BTreeTupleGetNPosting(itup);
+ memcpy(dedupState->ipd + dedupState->ntuples,
+ BTreeTupleGetPosting(itup),
+ sizeof(ItemPointerData) * nposting);
+ dedupState->ntuples += nposting;
+ }
+
+ /*
+ * Update the number of deduplicated items, belonging to this group.
+ * Count each item just once, no matter if it was posting tuple or not
+ */
+ dedupState->dedup_intervals[dedupState->n_intervals - 1].ntups++;
+
+ /* TODO just a debug message. delete it in final version of the patch */
+ if (itup_offnum != InvalidOffsetNumber)
+ elog(DEBUG4, "_bt_stash_item_tid. N %d : from %u ntups %u",
+ dedupState->n_intervals,
+ dedupState->dedup_intervals[dedupState->n_intervals - 1].from,
+ dedupState->dedup_intervals[dedupState->n_intervals - 1].ntups);
+}
+
+/*
* Read tuples in correct sort order from tuplesort, and load them into
* btree leaves.
*/
@@ -1141,9 +1282,20 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
bool load1;
TupleDesc tupdes = RelationGetDescr(wstate->index);
int i,
- keysz = IndexRelationGetNumberOfKeyAttributes(wstate->index);
+ keysz = IndexRelationGetNumberOfKeyAttributes(wstate->index),
+ natts = IndexRelationGetNumberOfAttributes(wstate->index);
SortSupport sortKeys;
int64 tuples_done = 0;
+ bool deduplicate = false;
+ BTDedupState *dedupState = NULL;
+
+ /*
+ * Don't use deduplication for indexes with INCLUDEd columns and unique
+ * indexes
+ */
+ deduplicate = (IndexRelationGetNumberOfKeyAttributes(wstate->index) ==
+ IndexRelationGetNumberOfAttributes(wstate->index) &&
+ !wstate->index->rd_index->indisunique);
if (merge)
{
@@ -1257,19 +1409,88 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2)
}
else
{
- /* merge is unnecessary */
- while ((itup = tuplesort_getindextuple(btspool->sortstate,
- true)) != NULL)
+ if (!deduplicate)
{
- /* When we see first tuple, create first index page */
- if (state == NULL)
- state = _bt_pagestate(wstate, 0);
+ /* merge is unnecessary */
+ while ((itup = tuplesort_getindextuple(btspool->sortstate,
+ true)) != NULL)
+ {
+ /* When we see first tuple, create first index page */
+ if (state == NULL)
+ state = _bt_pagestate(wstate, 0);
- _bt_buildadd(wstate, state, itup);
+ _bt_buildadd(wstate, state, itup);
- /* Report progress */
- pgstat_progress_update_param(PROGRESS_CREATEIDX_TUPLES_DONE,
- ++tuples_done);
+ /* Report progress */
+ pgstat_progress_update_param(PROGRESS_CREATEIDX_TUPLES_DONE,
+ ++tuples_done);
+ }
+ }
+ else
+ {
+ /* init deduplication state needed to build posting tuples */
+ dedupState = (BTDedupState *) palloc0(sizeof(BTDedupState));
+ dedupState->ipd = NULL;
+ dedupState->ntuples = 0;
+ dedupState->itupprev = NULL;
+ dedupState->maxitemsize = 0;
+ dedupState->maxpostingsize = 0;
+
+ while ((itup = tuplesort_getindextuple(btspool->sortstate,
+ true)) != NULL)
+ {
+ /* When we see first tuple, create first index page */
+ if (state == NULL)
+ {
+ state = _bt_pagestate(wstate, 0);
+ dedupState->maxitemsize = BTMaxItemSize(state->btps_page);
+ }
+
+ if (dedupState->itupprev != NULL)
+ {
+ int n_equal_atts = _bt_keep_natts_fast(wstate->index,
+ dedupState->itupprev, itup);
+
+ if (n_equal_atts > natts)
+ {
+ /*
+ * Tuples are equal. Create or update posting.
+ *
+ * Else If posting is too big, insert it on page and
+ * continue.
+ */
+ if ((dedupState->ntuples + 1) * sizeof(ItemPointerData) <
+ dedupState->maxpostingsize)
+ _bt_stash_item_tid(dedupState, itup, InvalidOffsetNumber);
+ else
+ _bt_buildadd_posting(wstate, state, dedupState);
+ }
+ else
+ {
+ /*
+ * Tuples are not equal. Insert itupprev into index.
+ * Save current tuple for the next iteration.
+ */
+ _bt_buildadd_posting(wstate, state, dedupState);
+ }
+ }
+
+ /*
+ * Save the tuple to compare it with the next one and maybe
+ * unite them into a posting tuple.
+ */
+ if (dedupState->itupprev)
+ pfree(dedupState->itupprev);
+ dedupState->itupprev = CopyIndexTuple(itup);
+
+ /* compute max size of posting list */
+ dedupState->maxpostingsize = dedupState->maxitemsize -
+ IndexInfoFindDataOffset(dedupState->itupprev->t_info) -
+ MAXALIGN(IndexTupleSize(dedupState->itupprev));
+ }
+
+ /* Handle the last item */
+ _bt_buildadd_posting(wstate, state, dedupState);
}
}
diff --git a/src/backend/access/nbtree/nbtsplitloc.c b/src/backend/access/nbtree/nbtsplitloc.c
index 1c1029b..54cecc8 100644
--- a/src/backend/access/nbtree/nbtsplitloc.c
+++ b/src/backend/access/nbtree/nbtsplitloc.c
@@ -183,6 +183,9 @@ _bt_findsplitloc(Relation rel,
state.minfirstrightsz = SIZE_MAX;
state.newitemoff = newitemoff;
+ /* newitem cannot be a posting list item */
+ Assert(!BTreeTupleIsPosting(newitem));
+
/*
* maxsplits should never exceed maxoff because there will be at most as
* many candidate split points as there are points _between_ tuples, once
@@ -459,17 +462,52 @@ _bt_recsplitloc(FindSplitData *state,
int16 leftfree,
rightfree;
Size firstrightitemsz;
+ Size postingsubhikey = 0;
bool newitemisfirstonright;
/* Is the new item going to be the first item on the right page? */
newitemisfirstonright = (firstoldonright == state->newitemoff
&& !newitemonleft);
+ /*
+ * FIXME: Accessing every single tuple like this adds cycles to cases that
+ * cannot possibly benefit (i.e. cases where we know that there cannot be
+ * posting lists). Maybe we should add a way to not bother when we are
+ * certain that this is the case.
+ *
+ * We could either have _bt_split() pass us a flag, or invent a page flag
+ * that indicates that the page might have posting lists, as an
+ * optimization. There is no shortage of btpo_flags bits for stuff like
+ * this.
+ */
if (newitemisfirstonright)
+ {
firstrightitemsz = state->newitemsz;
+
+ /* Calculate posting list overhead, if any */
+ if (state->is_leaf && BTreeTupleIsPosting(state->newitem))
+ postingsubhikey = IndexTupleSize(state->newitem) -
+ BTreeTupleGetPostingOffset(state->newitem);
+ }
else
+ {
firstrightitemsz = firstoldonrightsz;
+ /* Calculate posting list overhead, if any */
+ if (state->is_leaf)
+ {
+ ItemId itemid;
+ IndexTuple newhighkey;
+
+ itemid = PageGetItemId(state->page, firstoldonright);
+ newhighkey = (IndexTuple) PageGetItem(state->page, itemid);
+
+ if (BTreeTupleIsPosting(newhighkey))
+ postingsubhikey = IndexTupleSize(newhighkey) -
+ BTreeTupleGetPostingOffset(newhighkey);
+ }
+ }
+
/* Account for all the old tuples */
leftfree = state->leftspace - olddataitemstoleft;
rightfree = state->rightspace -
@@ -492,9 +530,13 @@ _bt_recsplitloc(FindSplitData *state,
* adding a heap TID to the left half's new high key when splitting at the
* leaf level. In practice the new high key will often be smaller and
* will rarely be larger, but conservatively assume the worst case.
+ * Truncation always truncates away any posting list that appears in the
+ * first right tuple, though, so it's safe to subtract that overhead
+ * (while still conservatively assuming that truncation might have to add
+ * back a single heap TID using the pivot tuple heap TID representation).
*/
if (state->is_leaf)
- leftfree -= (int16) (firstrightitemsz +
+ leftfree -= (int16) ((firstrightitemsz - postingsubhikey) +
MAXALIGN(sizeof(ItemPointerData)));
else
leftfree -= (int16) firstrightitemsz;
@@ -691,7 +733,8 @@ _bt_afternewitemoff(FindSplitData *state, OffsetNumber maxoff,
itemid = PageGetItemId(state->page, OffsetNumberPrev(state->newitemoff));
tup = (IndexTuple) PageGetItem(state->page, itemid);
/* Do cheaper test first */
- if (!_bt_adjacenthtid(&tup->t_tid, &state->newitem->t_tid))
+ if (BTreeTupleIsPosting(tup) ||
+ !_bt_adjacenthtid(&tup->t_tid, &state->newitem->t_tid))
return false;
/* Check same conditions as rightmost item case, too */
keepnatts = _bt_keep_natts_fast(state->rel, tup, state->newitem);
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 4c7b2d0..e3d7f4f 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -97,8 +97,6 @@ _bt_mkscankey(Relation rel, IndexTuple itup)
indoption = rel->rd_indoption;
tupnatts = itup ? BTreeTupleGetNAtts(itup, rel) : 0;
- Assert(tupnatts <= IndexRelationGetNumberOfAttributes(rel));
-
/*
* We'll execute search using scan key constructed on key columns.
* Truncated attributes and non-key attributes are omitted from the final
@@ -110,9 +108,20 @@ _bt_mkscankey(Relation rel, IndexTuple itup)
key->anynullkeys = false; /* initial assumption */
key->nextkey = false;
key->pivotsearch = false;
+ key->scantid = NULL;
key->keysz = Min(indnkeyatts, tupnatts);
- key->scantid = key->heapkeyspace && itup ?
- BTreeTupleGetHeapTID(itup) : NULL;
+
+ Assert(tupnatts <= IndexRelationGetNumberOfAttributes(rel));
+ Assert(!itup || !BTreeTupleIsPosting(itup) || key->heapkeyspace);
+
+ /*
+ * When caller passes a tuple with a heap TID, use it to set scantid. Note
+ * that this handles posting list tuples by setting scantid to the lowest
+ * heap TID in the posting list.
+ */
+ if (itup && key->heapkeyspace)
+ key->scantid = BTreeTupleGetHeapTID(itup);
+
skey = key->scankeys;
for (i = 0; i < indnkeyatts; i++)
{
@@ -1786,10 +1795,35 @@ _bt_killitems(IndexScanDesc scan)
{
ItemId iid = PageGetItemId(page, offnum);
IndexTuple ituple = (IndexTuple) PageGetItem(page, iid);
+ bool killtuple = false;
- if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid))
+ if (BTreeTupleIsPosting(ituple))
{
- /* found the item */
+ int pi = i + 1;
+ int nposting = BTreeTupleGetNPosting(ituple);
+ int j;
+
+ for (j = 0; j < nposting; j++)
+ {
+ ItemPointer item = BTreeTupleGetPostingN(ituple, j);
+
+ if (!ItemPointerEquals(item, &kitem->heapTid))
+ break; /* out of posting list loop */
+
+ /* Read-ahead to later kitems */
+ if (pi < numKilled)
+ kitem = &so->currPos.items[so->killedItems[pi++]];
+ }
+
+ if (j == nposting)
+ killtuple = true;
+ }
+ else if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid))
+ killtuple = true;
+
+ if (killtuple)
+ {
+ /* found the item/all posting list items */
ItemIdMarkDead(iid);
killedsomething = true;
break; /* out of inner search loop */
@@ -2145,6 +2179,24 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
pivot = index_truncate_tuple(itupdesc, firstright, keepnatts);
+ if (BTreeTupleIsPosting(firstright))
+ {
+ BTreeTupleClearBtIsPosting(pivot);
+ BTreeTupleSetNAtts(pivot, keepnatts);
+ if (keepnatts == natts)
+ {
+ /*
+ * index_truncate_tuple() just returned a copy of the
+ * original, so make sure that the size of the new pivot tuple
+ * doesn't have posting list overhead
+ */
+ pivot->t_info &= ~INDEX_SIZE_MASK;
+ pivot->t_info |= MAXALIGN(BTreeTupleGetPostingOffset(firstright));
+ }
+ }
+
+ Assert(!BTreeTupleIsPosting(pivot));
+
/*
* If there is a distinguishing key attribute within new pivot tuple,
* there is no need to add an explicit heap TID attribute
@@ -2161,6 +2213,8 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* attribute to the new pivot tuple.
*/
Assert(natts != nkeyatts);
+ Assert(!BTreeTupleIsPosting(lastleft) &&
+ !BTreeTupleIsPosting(firstright));
newsize = IndexTupleSize(pivot) + MAXALIGN(sizeof(ItemPointerData));
tidpivot = palloc0(newsize);
memcpy(tidpivot, pivot, IndexTupleSize(pivot));
@@ -2168,6 +2222,24 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
pfree(pivot);
pivot = tidpivot;
}
+ else if (BTreeTupleIsPosting(firstright))
+ {
+ /*
+ * No truncation was possible, since key attributes are all equal. We
+ * can always truncate away a posting list, though.
+ *
+ * It's necessary to add a heap TID attribute to the new pivot tuple.
+ */
+ newsize = MAXALIGN(BTreeTupleGetPostingOffset(firstright)) +
+ MAXALIGN(sizeof(ItemPointerData));
+ pivot = palloc0(newsize);
+ memcpy(pivot, firstright, BTreeTupleGetPostingOffset(firstright));
+
+ pivot->t_info &= ~INDEX_SIZE_MASK;
+ pivot->t_info |= newsize;
+ BTreeTupleClearBtIsPosting(pivot);
+ BTreeTupleSetAltHeapTID(pivot);
+ }
else
{
/*
@@ -2175,7 +2247,8 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* It's necessary to add a heap TID attribute to the new pivot tuple.
*/
Assert(natts == nkeyatts);
- newsize = IndexTupleSize(firstright) + MAXALIGN(sizeof(ItemPointerData));
+ newsize = MAXALIGN(IndexTupleSize(firstright)) +
+ MAXALIGN(sizeof(ItemPointerData));
pivot = palloc0(newsize);
memcpy(pivot, firstright, IndexTupleSize(firstright));
}
@@ -2193,6 +2266,7 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* nbtree (e.g., there is no pg_attribute entry).
*/
Assert(itup_key->heapkeyspace);
+ Assert(!BTreeTupleIsPosting(pivot));
pivot->t_info &= ~INDEX_SIZE_MASK;
pivot->t_info |= newsize;
@@ -2205,7 +2279,7 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
*/
pivotheaptid = (ItemPointer) ((char *) pivot + newsize -
sizeof(ItemPointerData));
- ItemPointerCopy(&lastleft->t_tid, pivotheaptid);
+ ItemPointerCopy(BTreeTupleGetMaxTID(lastleft), pivotheaptid);
/*
* Lehman and Yao require that the downlink to the right page, which is to
@@ -2216,9 +2290,12 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* tiebreaker.
*/
#ifndef DEBUG_NO_TRUNCATE
- Assert(ItemPointerCompare(&lastleft->t_tid, &firstright->t_tid) < 0);
- Assert(ItemPointerCompare(pivotheaptid, &lastleft->t_tid) >= 0);
- Assert(ItemPointerCompare(pivotheaptid, &firstright->t_tid) < 0);
+ Assert(ItemPointerCompare(BTreeTupleGetMaxTID(lastleft),
+ BTreeTupleGetHeapTID(firstright)) < 0);
+ Assert(ItemPointerCompare(pivotheaptid,
+ BTreeTupleGetHeapTID(lastleft)) >= 0);
+ Assert(ItemPointerCompare(pivotheaptid,
+ BTreeTupleGetHeapTID(firstright)) < 0);
#else
/*
@@ -2231,7 +2308,7 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* attribute values along with lastleft's heap TID value when lastleft's
* TID happens to be greater than firstright's TID.
*/
- ItemPointerCopy(&firstright->t_tid, pivotheaptid);
+ ItemPointerCopy(BTreeTupleGetHeapTID(firstright), pivotheaptid);
/*
* Pivot heap TID should never be fully equal to firstright. Note that
@@ -2240,7 +2317,8 @@ _bt_truncate(Relation rel, IndexTuple lastleft, IndexTuple firstright,
*/
ItemPointerSetOffsetNumber(pivotheaptid,
OffsetNumberPrev(ItemPointerGetOffsetNumber(pivotheaptid)));
- Assert(ItemPointerCompare(pivotheaptid, &firstright->t_tid) < 0);
+ Assert(ItemPointerCompare(pivotheaptid,
+ BTreeTupleGetHeapTID(firstright)) < 0);
#endif
BTreeTupleSetNAtts(pivot, nkeyatts);
@@ -2321,15 +2399,25 @@ _bt_keep_natts(Relation rel, IndexTuple lastleft, IndexTuple firstright,
* The approach taken here usually provides the same answer as _bt_keep_natts
* will (for the same pair of tuples from a heapkeyspace index), since the
* majority of btree opclasses can never indicate that two datums are equal
- * unless they're bitwise equal (once detoasted). Similarly, result may
- * differ from the _bt_keep_natts result when either tuple has TOASTed datums,
- * though this is barely possible in practice.
+ * unless they're bitwise equal after detoasting.
*
* These issues must be acceptable to callers, typically because they're only
* concerned about making suffix truncation as effective as possible without
* leaving excessive amounts of free space on either side of page split.
* Callers can rely on the fact that attributes considered equal here are
* definitely also equal according to _bt_keep_natts.
+ *
+ * When an index only uses opclasses where equality is "precise", this
+ * function is guaranteed to give the same result as _bt_keep_natts(). This
+ * makes it safe to use this function to determine whether or not two tuples
+ * can be folded together into a single posting tuple. Posting list
+ * deduplication cannot be used with nondeterministic collations for this
+ * reason.
+ *
+ * FIXME: Actually invent the needed "equality-is-precise" opclass
+ * infrastructure. See dedicated -hackers thread:
+ *
+ * https://postgr.es/m/CAH2-Wzn3Ee49Gmxb7V1VJ3-AC8fWn-Fr8pfWQebHe8rYRxt5OQ@mail.gmail.com
*/
int
_bt_keep_natts_fast(Relation rel, IndexTuple lastleft, IndexTuple firstright)
@@ -2354,8 +2442,38 @@ _bt_keep_natts_fast(Relation rel, IndexTuple lastleft, IndexTuple firstright)
if (isNull1 != isNull2)
break;
+ /*
+ * XXX: The ideal outcome from the point of view of the posting list
+ * patch is that the definition of an opclass with "precise equality"
+ * becomes: "equality operator function must give exactly the same
+ * answer as datum_image_eq() would, provided that we aren't using a
+ * nondeterministic collation". (Nondeterministic collations are
+ * clearly not compatible with deduplication.)
+ *
+ * This will be a lot faster than actually using the authoritative
+ * insertion scankey in some cases. This approach also seems more
+ * elegant, since suffix truncation gets to follow exactly the same
+ * definition of "equal" as posting list deduplication -- there is a
+ * subtle interplay between deduplication and suffix truncation, and
+ * it would be nice to know for sure that they have exactly the same
+ * idea about what equality is.
+ *
+ * This ideal outcome still avoids problems with TOAST. We cannot
+ * repeat bugs like the amcheck bug that was fixed in bugfix commit
+ * eba775345d23d2c999bbb412ae658b6dab36e3e8. datum_image_eq()
+ * considers binary equality, though only _after_ each datum is
+ * decompressed.
+ *
+ * If this ideal solution isn't possible, then we can fall back on
+ * defining "precise equality" as: "type's output function must
+ * produce identical textual output for any two datums that compare
+ * equal when using a safe/equality-is-precise operator class (unless
+ * using a nondeterministic collation)". That would mean that we'd
+ * have to make deduplication call _bt_keep_natts() instead (or some
+ * other function that uses authoritative insertion scankey).
+ */
if (!isNull1 &&
- !datumIsEqual(datum1, datum2, att->attbyval, att->attlen))
+ !datum_image_eq(datum1, datum2, att->attbyval, att->attlen))
break;
keepnatts++;
@@ -2407,22 +2525,30 @@ _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
tupnatts = BTreeTupleGetNAtts(itup, rel);
+ /* !heapkeyspace indexes do not support deduplication */
+ if (!heapkeyspace && BTreeTupleIsPosting(itup))
+ return false;
+
+ /* INCLUDE indexes do not support deduplication */
+ if (natts != nkeyatts && BTreeTupleIsPosting(itup))
+ return false;
+
if (P_ISLEAF(opaque))
{
if (offnum >= P_FIRSTDATAKEY(opaque))
{
/*
- * Non-pivot tuples currently never use alternative heap TID
- * representation -- even those within heapkeyspace indexes
+ * Non-pivot tuple should never be explicitly marked as a pivot
+ * tuple
*/
- if ((itup->t_info & INDEX_ALT_TID_MASK) != 0)
+ if (BTreeTupleIsPivot(itup))
return false;
/*
* Leaf tuples that are not the page high key (non-pivot tuples)
* should never be truncated. (Note that tupnatts must have been
- * inferred, rather than coming from an explicit on-disk
- * representation.)
+ * inferred, even with a posting list tuple, because only pivot
+ * tuples store tupnatts directly.)
*/
return tupnatts == natts;
}
@@ -2466,12 +2592,12 @@ _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
* non-zero, or when there is no explicit representation and the
* tuple is evidently not a pre-pg_upgrade tuple.
*
- * Prior to v11, downlinks always had P_HIKEY as their offset. Use
- * that to decide if the tuple is a pre-v11 tuple.
+ * Prior to v11, downlinks always had P_HIKEY as their offset.
+ * Accept that as an alternative indication of a valid
+ * !heapkeyspace negative infinity tuple.
*/
return tupnatts == 0 ||
- ((itup->t_info & INDEX_ALT_TID_MASK) == 0 &&
- ItemPointerGetOffsetNumber(&(itup->t_tid)) == P_HIKEY);
+ ItemPointerGetOffsetNumber(&(itup->t_tid)) == P_HIKEY;
}
else
{
@@ -2497,7 +2623,11 @@ _bt_check_natts(Relation rel, bool heapkeyspace, Page page, OffsetNumber offnum)
* heapkeyspace index pivot tuples, regardless of whether or not there are
* non-key attributes.
*/
- if ((itup->t_info & INDEX_ALT_TID_MASK) == 0)
+ if (!BTreeTupleIsPivot(itup))
+ return false;
+
+ /* Pivot tuple should not use posting list representation (redundant) */
+ if (BTreeTupleIsPosting(itup))
return false;
/*
@@ -2567,11 +2697,87 @@ _bt_check_third_page(Relation rel, Relation heap, bool needheaptidspace,
BTMaxItemSizeNoHeapTid(page),
RelationGetRelationName(rel)),
errdetail("Index row references tuple (%u,%u) in relation \"%s\".",
- ItemPointerGetBlockNumber(&newtup->t_tid),
- ItemPointerGetOffsetNumber(&newtup->t_tid),
+ ItemPointerGetBlockNumber(BTreeTupleGetHeapTID(newtup)),
+ ItemPointerGetOffsetNumber(BTreeTupleGetHeapTID(newtup)),
RelationGetRelationName(heap)),
errhint("Values larger than 1/3 of a buffer page cannot be indexed.\n"
"Consider a function index of an MD5 hash of the value, "
"or use full text indexing."),
errtableconstraint(heap, RelationGetRelationName(rel))));
}
+
+/*
+ * Given a basic tuple that contains key datum and posting list,
+ * build a posting tuple.
+ *
+ * Basic tuple can be a posting tuple, but we only use key part of it,
+ * all ItemPointers must be passed via ipd.
+ *
+ * If nipd == 1 fallback to building a non-posting tuple.
+ * It is necessary to avoid storage overhead after posting tuple was vacuumed.
+ */
+IndexTuple
+BTreeFormPostingTuple(IndexTuple tuple, ItemPointerData *ipd, int nipd)
+{
+ uint32 keysize,
+ newsize = 0;
+ IndexTuple itup;
+
+ /* We only need key part of the tuple */
+ if (BTreeTupleIsPosting(tuple))
+ keysize = BTreeTupleGetPostingOffset(tuple);
+ else
+ keysize = IndexTupleSize(tuple);
+
+ Assert(nipd > 0);
+
+ /* Add space needed for posting list */
+ if (nipd > 1)
+ newsize = SHORTALIGN(keysize) + sizeof(ItemPointerData) * nipd;
+ else
+ newsize = keysize;
+
+ newsize = MAXALIGN(newsize);
+ itup = palloc0(newsize);
+ memcpy(itup, tuple, keysize);
+ itup->t_info &= ~INDEX_SIZE_MASK;
+ itup->t_info |= newsize;
+
+ if (nipd > 1)
+ {
+ /* Form posting tuple, fill posting fields */
+
+ /* Set meta info about the posting list */
+ itup->t_info |= INDEX_ALT_TID_MASK;
+ BTreeSetPostingMeta(itup, nipd, SHORTALIGN(keysize));
+
+ /* sort the list to preserve TID order invariant */
+ qsort((void *) ipd, nipd, sizeof(ItemPointerData),
+ (int (*) (const void *, const void *)) ItemPointerCompare);
+
+ /* Copy posting list into the posting tuple */
+ memcpy(BTreeTupleGetPosting(itup), ipd,
+ sizeof(ItemPointerData) * nipd);
+ }
+ else
+ {
+ /* To finish building of a non-posting tuple, copy TID from ipd */
+ itup->t_info &= ~INDEX_ALT_TID_MASK;
+ ItemPointerCopy(ipd, &itup->t_tid);
+ }
+
+ return itup;
+}
+
+/*
+ * Opposite of BTreeFormPostingTuple.
+ * returns regular tuple that contains the key,
+ * the tid of the new tuple is the nth tid of original tuple's posting list
+ * result tuple palloc'd in a caller's context.
+ */
+IndexTuple
+BTreeGetNthTupleOfPosting(IndexTuple tuple, int n)
+{
+ Assert(BTreeTupleIsPosting(tuple));
+ return BTreeFormPostingTuple(tuple, BTreeTupleGetPostingN(tuple, n), 1);
+}
diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
index dd5315c..de9bc3b 100644
--- a/src/backend/access/nbtree/nbtxlog.c
+++ b/src/backend/access/nbtree/nbtxlog.c
@@ -181,9 +181,35 @@ btree_xlog_insert(bool isleaf, bool ismeta, XLogReaderState *record)
page = BufferGetPage(buffer);
- if (PageAddItem(page, (Item) datapos, datalen, xlrec->offnum,
- false, false) == InvalidOffsetNumber)
- elog(PANIC, "btree_xlog_insert: failed to add item");
+ if (xlrec->in_posting_offset != InvalidOffsetNumber)
+ {
+ /* oposting must be at offset before new item */
+ ItemId itemid = PageGetItemId(page, OffsetNumberPrev(xlrec->offnum));
+ IndexTuple oposting = (IndexTuple) PageGetItem(page, itemid);
+ IndexTuple newitem = (IndexTuple) datapos;
+ IndexTuple nposting;
+
+ nposting = _bt_form_newposting(newitem, oposting,
+ xlrec->in_posting_offset);
+ Assert(isleaf);
+
+ Assert(MAXALIGN(IndexTupleSize(oposting)) ==
+ MAXALIGN(IndexTupleSize(nposting)));
+
+ /* replace existing posting */
+ memcpy(oposting, nposting, MAXALIGN(IndexTupleSize(nposting)));
+
+ /* insert new item */
+ if (PageAddItem(page, (Item) newitem, MAXALIGN(IndexTupleSize(newitem)),
+ xlrec->offnum, false, false) == InvalidOffsetNumber)
+ elog(PANIC, "btree_xlog_insert: failed to add item");
+ }
+ else
+ {
+ if (PageAddItem(page, (Item) datapos, datalen, xlrec->offnum,
+ false, false) == InvalidOffsetNumber)
+ elog(PANIC, "btree_xlog_insert: failed to add item");
+ }
PageSetLSN(page, lsn);
MarkBufferDirty(buffer);
@@ -265,20 +291,43 @@ btree_xlog_split(bool onleft, XLogReaderState *record)
BTPageOpaque lopaque = (BTPageOpaque) PageGetSpecialPointer(lpage);
OffsetNumber off;
IndexTuple newitem = NULL,
- left_hikey = NULL;
+ left_hikey = NULL,
+ nposting = NULL;
Size newitemsz = 0,
left_hikeysz = 0;
Page newlpage;
- OffsetNumber leftoff;
+ OffsetNumber leftoff,
+ replacepostingoff = InvalidOffsetNumber;
datapos = XLogRecGetBlockData(record, 0, &datalen);
- if (onleft)
+ if (onleft || xlrec->in_posting_offset)
{
newitem = (IndexTuple) datapos;
newitemsz = MAXALIGN(IndexTupleSize(newitem));
datapos += newitemsz;
datalen -= newitemsz;
+
+ /*
+ * Repeat logic implemented in _bt_insertonpg():
+ *
+ * If the new tuple is a duplicate with a heap TID that falls
+ * inside the range of an existing posting list tuple,
+ * generate new posting tuple to replace original one
+ * and update new tuple so that it's heap TID contains
+ * the rightmost heap TID of original posting tuple.
+ */
+ if (xlrec->in_posting_offset)
+ {
+ ItemId itemid = PageGetItemId(lpage, xlrec->newitemoff);
+ IndexTuple oposting = (IndexTuple) PageGetItem(lpage, itemid);
+
+ nposting = _bt_form_newposting(newitem, oposting,
+ xlrec->in_posting_offset);
+ /* Alter new item offset, since effective new item changed */
+ xlrec->newitemoff = OffsetNumberNext(xlrec->newitemoff);
+ replacepostingoff = OffsetNumberPrev(xlrec->newitemoff);
+ }
}
/* Extract left hikey and its size (assuming 16-bit alignment) */
@@ -304,6 +353,15 @@ btree_xlog_split(bool onleft, XLogReaderState *record)
Size itemsz;
IndexTuple item;
+ if (off == replacepostingoff)
+ {
+ if (PageAddItem(newlpage, (Item) nposting, MAXALIGN(IndexTupleSize(nposting)),
+ leftoff, false, false) == InvalidOffsetNumber)
+ elog(ERROR, "failed to add new item to left page after split");
+ leftoff = OffsetNumberNext(leftoff);
+ continue;
+ }
+
/* add the new item if it was inserted on left page */
if (onleft && off == xlrec->newitemoff)
{
@@ -380,14 +438,146 @@ btree_xlog_split(bool onleft, XLogReaderState *record)
}
static void
+btree_xlog_dedup(XLogReaderState *record)
+{
+ XLogRecPtr lsn = record->EndRecPtr;
+ Buffer buf;
+ Page newpage;
+ xl_btree_dedup *xlrec = (xl_btree_dedup *) XLogRecGetData(record);
+
+ if (XLogReadBufferForRedo(record, 0, &buf) == BLK_NEEDS_REDO)
+ {
+ /*
+ * Initialize a temporary empty page and copy all the items
+ * to that in item number order.
+ */
+ Page page = (Page) BufferGetPage(buf);
+ BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
+ BTPageOpaque nopaque;
+ OffsetNumber offnum, minoff, maxoff;
+ BTDedupState *dedupState = NULL;
+ char *data = ((char *) xlrec + SizeOfBtreeDedup);
+ dedupInterval dedup_intervals[MaxOffsetNumber];
+ int nth_interval = 0;
+ OffsetNumber n_dedup_tups = 0;
+
+ dedupState = (BTDedupState *) palloc0(sizeof(BTDedupState));
+ dedupState->ipd = NULL;
+ dedupState->ntuples = 0;
+ dedupState->itupprev = NULL;
+ dedupState->maxitemsize = BTMaxItemSize(page);
+ dedupState->maxpostingsize = 0;
+
+ memcpy(dedup_intervals, data,
+ xlrec->n_intervals*sizeof(dedupInterval));
+
+ /* Scan over all items to see which ones can be deduplicated */
+ minoff = P_FIRSTDATAKEY(opaque);
+ maxoff = PageGetMaxOffsetNumber(page);
+ newpage = PageGetTempPageCopySpecial(page);
+ nopaque = (BTPageOpaque) PageGetSpecialPointer(newpage);
+
+ /* Make sure that new page won't have garbage flag set */
+ nopaque->btpo_flags &= ~BTP_HAS_GARBAGE;
+
+ /* Copy High Key if any */
+ if (!P_RIGHTMOST(opaque))
+ {
+ ItemId itemid = PageGetItemId(page, P_HIKEY);
+ Size itemsz = ItemIdGetLength(itemid);
+ IndexTuple item = (IndexTuple) PageGetItem(page, itemid);
+
+ if (PageAddItem(newpage, (Item) item, itemsz, P_HIKEY,
+ false, false) == InvalidOffsetNumber)
+ elog(ERROR, "failed to add highkey during deduplication");
+ }
+
+ /*
+ * Iterate over tuples on the page to deduplicate them into posting
+ * lists and insert into new page
+ */
+ for (offnum = minoff;
+ offnum <= maxoff;
+ offnum = OffsetNumberNext(offnum))
+ {
+ ItemId itemId = PageGetItemId(page, offnum);
+ IndexTuple itup = (IndexTuple) PageGetItem(page, itemId);
+
+ elog(DEBUG4, "btree_xlog_dedup. offnum %u, n_intervals %u, from %u ntups %u",
+ offnum,
+ nth_interval,
+ dedup_intervals[nth_interval].from,
+ dedup_intervals[nth_interval].ntups);
+
+ if (dedupState->itupprev == NULL)
+ {
+ /* Just set up base/first item in first iteration */
+ Assert(offnum == minoff);
+ dedupState->itupprev = CopyIndexTuple(itup);
+ dedupState->itupprev_off = offnum;
+ continue;
+ }
+
+ /*
+ * Instead of comparing tuple's keys, which may be costly, use
+ * information from xlog record. If current tuple belongs to the
+ * group of deduplicated items, repeat logic of _bt_dedup_one_page
+ * and stash it to form a posting list afterwards.
+ */
+ if (dedupState->itupprev_off >= dedup_intervals[nth_interval].from
+ && n_dedup_tups < dedup_intervals[nth_interval].ntups)
+ {
+ _bt_stash_item_tid(dedupState, itup, InvalidOffsetNumber);
+
+ elog(DEBUG4, "btree_xlog_dedup. stash offnum %u, nth_interval %u, from %u ntups %u",
+ offnum,
+ nth_interval,
+ dedup_intervals[nth_interval].from,
+ dedup_intervals[nth_interval].ntups);
+
+ /* count first tuple in the group */
+ if (dedupState->itupprev_off == dedup_intervals[nth_interval].from)
+ n_dedup_tups++;
+
+ /* count added tuple */
+ n_dedup_tups++;
+ }
+ else
+ {
+ _bt_dedup_insert(newpage, dedupState);
+
+ /* reset state */
+ if (n_dedup_tups > 0)
+ nth_interval++;
+ n_dedup_tups = 0;
+ }
+
+ pfree(dedupState->itupprev);
+ dedupState->itupprev = CopyIndexTuple(itup);
+ dedupState->itupprev_off = offnum;
+ }
+
+ /* Handle the last item */
+ _bt_dedup_insert(newpage, dedupState);
+
+ PageRestoreTempPage(newpage, page);
+ PageSetLSN(page, lsn);
+ MarkBufferDirty(buf);
+ }
+
+ if (BufferIsValid(buf))
+ UnlockReleaseBuffer(buf);
+}
+
+static void
btree_xlog_vacuum(XLogReaderState *record)
{
XLogRecPtr lsn = record->EndRecPtr;
Buffer buffer;
Page page;
BTPageOpaque opaque;
-#ifdef UNUSED
xl_btree_vacuum *xlrec = (xl_btree_vacuum *) XLogRecGetData(record);
+#ifdef UNUSED
/*
* This section of code is thought to be no longer needed, after analysis
@@ -478,14 +668,34 @@ btree_xlog_vacuum(XLogReaderState *record)
if (len > 0)
{
- OffsetNumber *unused;
- OffsetNumber *unend;
+ if (xlrec->nremaining)
+ {
+ OffsetNumber *remainingoffset;
+ IndexTuple remaining;
+ Size itemsz;
+
+ remainingoffset = (OffsetNumber *)
+ (ptr + xlrec->ndeleted * sizeof(OffsetNumber));
+ remaining = (IndexTuple) ((char *) remainingoffset +
+ xlrec->nremaining * sizeof(OffsetNumber));
+
+ /* Handle posting tuples */
+ for (int i = 0; i < xlrec->nremaining; i++)
+ {
+ PageIndexTupleDelete(page, remainingoffset[i]);
- unused = (OffsetNumber *) ptr;
- unend = (OffsetNumber *) ((char *) ptr + len);
+ itemsz = MAXALIGN(IndexTupleSize(remaining));
- if ((unend - unused) > 0)
- PageIndexMultiDelete(page, unused, unend - unused);
+ if (PageAddItem(page, (Item) remaining, itemsz, remainingoffset[i],
+ false, false) == InvalidOffsetNumber)
+ elog(PANIC, "btree_xlog_vacuum: failed to add remaining item");
+
+ remaining = (IndexTuple) ((char *) remaining + itemsz);
+ }
+ }
+
+ if (xlrec->ndeleted)
+ PageIndexMultiDelete(page, (OffsetNumber *) ptr, xlrec->ndeleted);
}
/*
@@ -838,6 +1048,9 @@ btree_redo(XLogReaderState *record)
case XLOG_BTREE_SPLIT_R:
btree_xlog_split(false, record);
break;
+ case XLOG_BTREE_DEDUP_PAGE:
+ btree_xlog_dedup(record);
+ break;
case XLOG_BTREE_VACUUM:
btree_xlog_vacuum(record);
break;
diff --git a/src/backend/access/rmgrdesc/nbtdesc.c b/src/backend/access/rmgrdesc/nbtdesc.c
index a14eb79..802e27b 100644
--- a/src/backend/access/rmgrdesc/nbtdesc.c
+++ b/src/backend/access/rmgrdesc/nbtdesc.c
@@ -30,7 +30,8 @@ btree_desc(StringInfo buf, XLogReaderState *record)
{
xl_btree_insert *xlrec = (xl_btree_insert *) rec;
- appendStringInfo(buf, "off %u", xlrec->offnum);
+ appendStringInfo(buf, "off %u; in_posting_offset %u",
+ xlrec->offnum, xlrec->in_posting_offset);
break;
}
case XLOG_BTREE_SPLIT_L:
@@ -38,16 +39,27 @@ btree_desc(StringInfo buf, XLogReaderState *record)
{
xl_btree_split *xlrec = (xl_btree_split *) rec;
+ /* FIXME: even master doesn't have newitemoff */
appendStringInfo(buf, "level %u, firstright %d",
xlrec->level, xlrec->firstright);
break;
}
+ case XLOG_BTREE_DEDUP_PAGE:
+ {
+ xl_btree_dedup *xlrec = (xl_btree_dedup *) rec;
+
+ appendStringInfo(buf, "items were deduplicated to %d items",
+ xlrec->n_intervals);
+ break;
+ }
case XLOG_BTREE_VACUUM:
{
xl_btree_vacuum *xlrec = (xl_btree_vacuum *) rec;
- appendStringInfo(buf, "lastBlockVacuumed %u",
- xlrec->lastBlockVacuumed);
+ appendStringInfo(buf, "lastBlockVacuumed %u; nremaining %u; ndeleted %u",
+ xlrec->lastBlockVacuumed,
+ xlrec->nremaining,
+ xlrec->ndeleted);
break;
}
case XLOG_BTREE_DELETE:
@@ -131,6 +143,9 @@ btree_identify(uint8 info)
case XLOG_BTREE_SPLIT_R:
id = "SPLIT_R";
break;
+ case XLOG_BTREE_DEDUP_PAGE:
+ id = "DEDUPLICATE";
+ break;
case XLOG_BTREE_VACUUM:
id = "VACUUM";
break;
diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 52eafe6..d1af18f 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -234,8 +234,7 @@ typedef struct BTMetaPageData
* t_tid | t_info | key values | INCLUDE columns, if any
*
* t_tid points to the heap TID, which is a tiebreaker key column as of
- * BTREE_VERSION 4. Currently, the INDEX_ALT_TID_MASK status bit is never
- * set for non-pivot tuples.
+ * BTREE_VERSION 4.
*
* All other types of index tuples ("pivot" tuples) only have key columns,
* since pivot tuples only exist to represent how the key space is
@@ -252,6 +251,38 @@ typedef struct BTMetaPageData
* omitted rather than truncated, since its representation is different to
* the non-pivot representation.)
*
+ * Non-pivot posting tuple format:
+ * t_tid | t_info | key values | INCLUDE columns, if any | posting_list[]
+ *
+ * In order to store duplicated keys more effectively, we use special format
+ * of tuples - posting tuples. posting_list is an array of ItemPointerData.
+ *
+ * Deduplication never applies to unique indexes or indexes with INCLUDEd
+ * columns.
+ *
+ * To differ posting tuples we use INDEX_ALT_TID_MASK flag in t_info and
+ * BT_IS_POSTING flag in t_tid.
+ * These flags redefine the content of the posting tuple's tid:
+ * - t_tid.ip_blkid contains offset of the posting list.
+ * - t_tid offset field contains number of posting items this tuple contain
+ *
+ * The 12 least significant offset bits from t_tid are used to represent
+ * the number of posting items in posting tuples, leaving 4 status
+ * bits (BT_RESERVED_OFFSET_MASK bits), 3 of which that are reserved for
+ * future use.
+ * BT_N_POSTING_OFFSET_MASK is large enough to store any number of posting
+ * tuples, which is constrainted by BTMaxItemSize.
+
+ * If page contains so many duplicates, that they do not fit into one posting
+ * tuple (bounded by BTMaxItemSize and ), page may contain several posting
+ * tuples with the same key.
+ * Also page can contain both posting and non-posting tuples with the same key.
+ * Currently, posting tuples always contain at least two TIDs in the posting
+ * list.
+ *
+ * Posting tuples always have the same number of attributes as the index has
+ * generally.
+ *
* Pivot tuple format:
*
* t_tid | t_info | key values | [heap TID]
@@ -281,23 +312,145 @@ typedef struct BTMetaPageData
* bits (BT_RESERVED_OFFSET_MASK bits), 3 of which that are reserved for
* future use. BT_N_KEYS_OFFSET_MASK should be large enough to store any
* number of columns/attributes <= INDEX_MAX_KEYS.
+ * BT_IS_POSTING bit must be unset for pivot tuples, since we use it
+ * to distinct posting tuples from pivot tuples.
*
* Note well: The macros that deal with the number of attributes in tuples
- * assume that a tuple with INDEX_ALT_TID_MASK set must be a pivot tuple,
- * and that a tuple without INDEX_ALT_TID_MASK set must be a non-pivot
- * tuple (or must have the same number of attributes as the index has
- * generally in the case of !heapkeyspace indexes). They will need to be
- * updated if non-pivot tuples ever get taught to use INDEX_ALT_TID_MASK
- * for something else.
+ * assume that a tuple with INDEX_ALT_TID_MASK set must be a pivot tuple or
+ * non-pivot posting tuple, and that a tuple without INDEX_ALT_TID_MASK set
+ * must be a non-pivot tuple (or must have the same number of attributes as
+ * the index has generally in the case of !heapkeyspace indexes).
*/
#define INDEX_ALT_TID_MASK INDEX_AM_RESERVED_BIT
/* Item pointer offset bits */
#define BT_RESERVED_OFFSET_MASK 0xF000
#define BT_N_KEYS_OFFSET_MASK 0x0FFF
+#define BT_N_POSTING_OFFSET_MASK 0x0FFF
#define BT_HEAP_TID_ATTR 0x1000
+#define BT_IS_POSTING 0x2000
+
+/*
+ * MaxPostingIndexTuplesPerPage is an upper bound on the number of tuples
+ * that can fit on one btree leaf page.
+ *
+ * Btree leaf pages may contain posting tuples, which store duplicates
+ * in a more effective way, so MaxPostingIndexTuplesPerPage is larger then
+ * MaxIndexTuplesPerPage.
+ *
+ * Each leaf page must contain at least three items, so estimate it as
+ * if we have three posting tuples with minimal size keys.
+ */
+#define MaxPostingIndexTuplesPerPage \
+ ((int) ((BLCKSZ - SizeOfPageHeaderData - \
+ 3*((MAXALIGN(sizeof(IndexTupleData) + 1) + sizeof(ItemIdData))) )) / \
+ (sizeof(ItemPointerData)))
+
+/*
+ * Helper for BTDedupState.
+ * Each entry represents a group of 'ntups' consecutive items starting on
+ * 'from' offset that were deduplicated into a single posting tuple.
+ */
+typedef struct dedupInterval
+{
+ OffsetNumber from;
+ OffsetNumber ntups;
+} dedupInterval;
+
+/*
+ * Btree-private state needed to build posting tuples.
+ * ipd is a posting list - an array of ItemPointerData.
+ *
+ * Iterating over tuples during index build or applying deduplication to a
+ * single page, we remember a tuple in itupprev, then compare the next one
+ * with it. If tuples are equal, save their TIDs in the posting list.
+ * ntuples contains the size of the posting list.
+ *
+ * Use maxitemsize and maxpostingsize to ensure that resulting posting tuple
+ * will satisfy BTMaxItemSize.
+ */
+typedef struct BTDedupState
+{
+ Size maxitemsize;
+ Size maxpostingsize;
+ IndexTuple itupprev;
+
+ /*
+ * array with info about deduplicated items on the page.
+ *
+ * It contains one entry for each group of consecutive items that
+ * were deduplicated into a single posting tuple.
+ *
+ * This array is saved to xlog entry, which allows to replay
+ * deduplication faster without actually comparing tuple's keys.
+ */
+ dedupInterval dedup_intervals[MaxOffsetNumber];
+ /* current number of items in dedup_intervals array */
+ int n_intervals;
+ /* temp state variable to keep a 'possible' start of dedup interval */
+ OffsetNumber itupprev_off;
+
+ int ntuples;
+ ItemPointerData *ipd;
+} BTDedupState;
+
+/*
+ * N.B.: BTreeTupleIsPivot() should only be used in code that deals with
+ * heapkeyspace indexes specifically. BTreeTupleIsPosting() works with all
+ * nbtree indexes, though.
+ */
+#define BTreeTupleIsPivot(itup) \
+ ( \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) == 0))\
+ )
+#define BTreeTupleIsPosting(itup) \
+ ( \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) != 0))\
+ )
+
+#define BTreeTupleClearBtIsPosting(itup) \
+ do { \
+ ItemPointerSetOffsetNumber(&(itup)->t_tid, \
+ ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & ~BT_IS_POSTING); \
+ } while(0)
+
+#define BTreeTupleGetNPosting(itup) \
+ ( \
+ AssertMacro(BTreeTupleIsPosting(itup)), \
+ ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_N_POSTING_OFFSET_MASK \
+ )
+#define BTreeTupleSetNPosting(itup, n) \
+ do { \
+ ItemPointerSetOffsetNumber(&(itup)->t_tid, (n) & BT_N_POSTING_OFFSET_MASK); \
+ Assert((itup)->t_info & INDEX_ALT_TID_MASK); \
+ Assert(!((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) != 0)); \
+ ItemPointerSetOffsetNumber(&(itup)->t_tid, \
+ ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) | BT_IS_POSTING); \
+ } while(0)
-/* Get/set downlink block number */
+/*
+ * If tuple is posting, t_tid.ip_blkid contains offset of the posting list
+ */
+#define BTreeTupleGetPostingOffset(itup) \
+ ( \
+ AssertMacro(BTreeTupleIsPosting(itup)), \
+ ItemPointerGetBlockNumberNoCheck(&((itup)->t_tid)) \
+ )
+#define BTreeSetPostingMeta(itup, nposting, off) \
+ do { \
+ BTreeTupleSetNPosting(itup, nposting); \
+ Assert(BTreeTupleIsPosting(itup)); \
+ ItemPointerSetBlockNumber(&((itup)->t_tid), (off)); \
+ } while(0)
+
+#define BTreeTupleGetPosting(itup) \
+ (ItemPointer) ((char*) (itup) + BTreeTupleGetPostingOffset(itup))
+#define BTreeTupleGetPostingN(itup,n) \
+ (BTreeTupleGetPosting(itup) + (n))
+
+/* Get/set downlink block number */
#define BTreeInnerTupleGetDownLink(itup) \
ItemPointerGetBlockNumberNoCheck(&((itup)->t_tid))
#define BTreeInnerTupleSetDownLink(itup, blkno) \
@@ -326,40 +479,73 @@ typedef struct BTMetaPageData
*/
#define BTreeTupleGetNAtts(itup, rel) \
( \
- (itup)->t_info & INDEX_ALT_TID_MASK ? \
+ ((itup)->t_info & INDEX_ALT_TID_MASK && \
+ ((ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_IS_POSTING) == 0)) ? \
( \
ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_N_KEYS_OFFSET_MASK \
) \
: \
IndexRelationGetNumberOfAttributes(rel) \
)
-#define BTreeTupleSetNAtts(itup, n) \
- do { \
- (itup)->t_info |= INDEX_ALT_TID_MASK; \
- ItemPointerSetOffsetNumber(&(itup)->t_tid, (n) & BT_N_KEYS_OFFSET_MASK); \
- } while(0)
+
+static inline void
+BTreeTupleSetNAtts(IndexTuple itup, int n)
+{
+ Assert(!BTreeTupleIsPosting(itup));
+ itup->t_info |= INDEX_ALT_TID_MASK;
+ ItemPointerSetOffsetNumber(&itup->t_tid, n & BT_N_KEYS_OFFSET_MASK);
+}
/*
- * Get tiebreaker heap TID attribute, if any. Macro works with both pivot
- * and non-pivot tuples, despite differences in how heap TID is represented.
+ * Get tiebreaker heap TID attribute, if any. Works with both pivot and
+ * non-pivot tuples, despite differences in how heap TID is represented.
+ *
+ * This returns the first/lowest heap TID in the case of a posting list tuple.
*/
-#define BTreeTupleGetHeapTID(itup) \
- ( \
- (itup)->t_info & INDEX_ALT_TID_MASK && \
- (ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) & BT_HEAP_TID_ATTR) != 0 ? \
- ( \
- (ItemPointer) (((char *) (itup) + IndexTupleSize(itup)) - \
- sizeof(ItemPointerData)) \
- ) \
- : (itup)->t_info & INDEX_ALT_TID_MASK ? NULL : (ItemPointer) &((itup)->t_tid) \
- )
+static inline ItemPointer
+BTreeTupleGetHeapTID(IndexTuple itup)
+{
+ if (BTreeTupleIsPivot(itup))
+ {
+ /* Pivot tuple heap TID representation? */
+ if ((ItemPointerGetOffsetNumberNoCheck(&itup->t_tid) &
+ BT_HEAP_TID_ATTR) != 0)
+ return (ItemPointer) ((char *) itup + IndexTupleSize(itup) -
+ sizeof(ItemPointerData));
+
+ /* Heap TID attribute was truncated */
+ return NULL;
+ }
+ else if (BTreeTupleIsPosting(itup))
+ return BTreeTupleGetPosting(itup);
+
+ return &(itup->t_tid);
+}
+
+/*
+ * Get maximum heap TID attribute, which could be the only TID in the case of
+ * a non-pivot tuple that does not have a posting list tuple. Works with
+ * non-pivot tuples only.
+ */
+static inline ItemPointer
+BTreeTupleGetMaxTID(IndexTuple itup)
+{
+ Assert(!BTreeTupleIsPivot(itup));
+
+ if (BTreeTupleIsPosting(itup))
+ return (ItemPointer) (BTreeTupleGetPosting(itup) +
+ (BTreeTupleGetNPosting(itup) - 1));
+
+ return &(itup->t_tid);
+}
+
/*
* Set the heap TID attribute for a tuple that uses the INDEX_ALT_TID_MASK
- * representation (currently limited to pivot tuples)
+ * representation
*/
#define BTreeTupleSetAltHeapTID(itup) \
do { \
- Assert((itup)->t_info & INDEX_ALT_TID_MASK); \
+ Assert(BTreeTupleIsPivot(itup)); \
ItemPointerSetOffsetNumber(&(itup)->t_tid, \
ItemPointerGetOffsetNumberNoCheck(&(itup)->t_tid) | BT_HEAP_TID_ATTR); \
} while(0)
@@ -500,6 +686,13 @@ typedef struct BTInsertStateData
Buffer buf;
/*
+ * if _bt_binsrch_insert() found the location inside existing posting
+ * list, save the position inside the list. This will be -1 in rare cases
+ * where the overlapping posting list is LP_DEAD.
+ */
+ int in_posting_offset;
+
+ /*
* Cache of bounds within the current buffer. Only used for insertions
* where _bt_check_unique is called. See _bt_binsrch_insert and
* _bt_findinsertloc for details.
@@ -534,7 +727,9 @@ typedef BTInsertStateData *BTInsertState;
* If we are doing an index-only scan, we save the entire IndexTuple for each
* matched item, otherwise only its heap TID and offset. The IndexTuples go
* into a separate workspace array; each BTScanPosItem stores its tuple's
- * offset within that array.
+ * offset within that array. Posting list tuples store a version of the
+ * tuple that does not include the posting list, allowing the same key to be
+ * returned for each logical tuple associated with the posting list.
*/
typedef struct BTScanPosItem /* what we remember about each match */
@@ -563,9 +758,13 @@ typedef struct BTScanPosData
/*
* If we are doing an index-only scan, nextTupleOffset is the first free
- * location in the associated tuple storage workspace.
+ * location in the associated tuple storage workspace. Posting list
+ * tuples need postingTupleOffset to store the current location of the
+ * tuple that is returned multiple times (once per heap TID in posting
+ * list).
*/
int nextTupleOffset;
+ int postingTupleOffset;
/*
* The items array is always ordered in index order (ie, increasing
@@ -578,7 +777,7 @@ typedef struct BTScanPosData
int lastItem; /* last valid index in items[] */
int itemIndex; /* current index in items[] */
- BTScanPosItem items[MaxIndexTuplesPerPage]; /* MUST BE LAST */
+ BTScanPosItem items[MaxPostingIndexTuplesPerPage]; /* MUST BE LAST */
} BTScanPosData;
typedef BTScanPosData *BTScanPos;
@@ -732,6 +931,9 @@ extern bool _bt_doinsert(Relation rel, IndexTuple itup,
IndexUniqueCheck checkUnique, Relation heapRel);
extern Buffer _bt_getstackbuf(Relation rel, BTStack stack, BlockNumber child);
extern void _bt_finish_split(Relation rel, Buffer bbuf, BTStack stack);
+extern IndexTuple _bt_form_newposting(IndexTuple itup, IndexTuple oposting,
+ OffsetNumber in_posting_offset);
+extern void _bt_dedup_insert(Page page, BTDedupState *dedupState);
/*
* prototypes for functions in nbtsplitloc.c
@@ -762,6 +964,8 @@ extern void _bt_delitems_delete(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems, Relation heapRel);
extern void _bt_delitems_vacuum(Relation rel, Buffer buf,
OffsetNumber *itemnos, int nitems,
+ OffsetNumber *remainingoffset,
+ IndexTuple *remaining, int nremaining,
BlockNumber lastBlockVacuumed);
extern int _bt_pagedel(Relation rel, Buffer buf);
@@ -812,6 +1016,9 @@ extern bool _bt_check_natts(Relation rel, bool heapkeyspace, Page page,
OffsetNumber offnum);
extern void _bt_check_third_page(Relation rel, Relation heap,
bool needheaptidspace, Page page, IndexTuple newtup);
+extern IndexTuple BTreeFormPostingTuple(IndexTuple tuple, ItemPointerData *ipd,
+ int nipd);
+extern IndexTuple BTreeGetNthTupleOfPosting(IndexTuple tuple, int n);
/*
* prototypes for functions in nbtvalidate.c
@@ -824,5 +1031,7 @@ extern bool btvalidate(Oid opclassoid);
extern IndexBuildResult *btbuild(Relation heap, Relation index,
struct IndexInfo *indexInfo);
extern void _bt_parallel_build_main(dsm_segment *seg, shm_toc *toc);
+extern void _bt_stash_item_tid(BTDedupState *dedupState, IndexTuple itup,
+ OffsetNumber itup_offnum);
#endif /* NBTREE_H */
diff --git a/src/include/access/nbtxlog.h b/src/include/access/nbtxlog.h
index afa614d..075baaf 100644
--- a/src/include/access/nbtxlog.h
+++ b/src/include/access/nbtxlog.h
@@ -28,7 +28,8 @@
#define XLOG_BTREE_INSERT_META 0x20 /* same, plus update metapage */
#define XLOG_BTREE_SPLIT_L 0x30 /* add index tuple with split */
#define XLOG_BTREE_SPLIT_R 0x40 /* as above, new item on right */
-/* 0x50 and 0x60 are unused */
+#define XLOG_BTREE_DEDUP_PAGE 0x50 /* compactify tuples on the page */
+/* 0x60 is unused */
#define XLOG_BTREE_DELETE 0x70 /* delete leaf index tuples for a page */
#define XLOG_BTREE_UNLINK_PAGE 0x80 /* delete a half-dead page */
#define XLOG_BTREE_UNLINK_PAGE_META 0x90 /* same, and update metapage */
@@ -61,16 +62,21 @@ typedef struct xl_btree_metadata
* This data record is used for INSERT_LEAF, INSERT_UPPER, INSERT_META.
* Note that INSERT_META implies it's not a leaf page.
*
- * Backup Blk 0: original page (data contains the inserted tuple)
+ * Backup Blk 0: original page (data contains the inserted tuple);
+ * if in_posting_offset is valid, this is an insertion
+ * into existing posting tuple at offnum.
+ * redo must repeat logic of bt_insertonpg().
* Backup Blk 1: child's left sibling, if INSERT_UPPER or INSERT_META
* Backup Blk 2: xl_btree_metadata, if INSERT_META
+ *
*/
typedef struct xl_btree_insert
{
OffsetNumber offnum;
+ OffsetNumber in_posting_offset;
} xl_btree_insert;
-#define SizeOfBtreeInsert (offsetof(xl_btree_insert, offnum) + sizeof(OffsetNumber))
+#define SizeOfBtreeInsert (offsetof(xl_btree_insert, in_posting_offset) + sizeof(OffsetNumber))
/*
* On insert with split, we save all the items going into the right sibling
@@ -96,6 +102,11 @@ typedef struct xl_btree_insert
* An IndexTuple representing the high key of the left page must follow with
* either variant.
*
+ * In case, split included insertion into the middle of the posting tuple, and
+ * thus required posting tuple replacement, it also contains 'in_posting_offset',
+ * that is used to form replacing tuple and repean bt_insertonpg() logic.
+ * It is added to xlog only if replacing item remains on the left page.
+ *
* Backup Blk 1: new right page
*
* The right page's data portion contains the right page's tuples in the form
@@ -113,9 +124,26 @@ typedef struct xl_btree_split
uint32 level; /* tree level of page being split */
OffsetNumber firstright; /* first item moved to right page */
OffsetNumber newitemoff; /* new item's offset (if placed on left page) */
+ OffsetNumber in_posting_offset; /* offset inside posting tuple */
} xl_btree_split;
-#define SizeOfBtreeSplit (offsetof(xl_btree_split, newitemoff) + sizeof(OffsetNumber))
+#define SizeOfBtreeSplit (offsetof(xl_btree_split, in_posting_offset) + sizeof(OffsetNumber))
+
+/*
+ * When page is deduplicated, consecutive groups of tuples with equal keys
+ * are compactified into posting tuples.
+ * The WAL record keeps number of resulting posting tuples - n_intervals
+ * followed by array of dedupInterval structures, that hold information
+ * needed to replay page deduplication without extra comparisons of tuples keys.
+ */
+typedef struct xl_btree_dedup
+{
+ int n_intervals;
+
+ /* TARGET DEDUP INTERVALS FOLLOW AT THE END */
+} xl_btree_dedup;
+#define SizeOfBtreeDedup (sizeof(int))
+
/*
* This is what we need to know about delete of individual leaf index tuples.
@@ -173,10 +201,19 @@ typedef struct xl_btree_vacuum
{
BlockNumber lastBlockVacuumed;
- /* TARGET OFFSET NUMBERS FOLLOW */
+ /*
+ * This field helps us to find beginning of the remaining tuples from
+ * postings which follow array of offset numbers.
+ */
+ uint32 nremaining;
+ uint32 ndeleted;
+
+ /* REMAINING OFFSET NUMBERS FOLLOW (nremaining values) */
+ /* REMAINING TUPLES TO INSERT FOLLOW (if nremaining > 0) */
+ /* TARGET OFFSET NUMBERS FOLLOW (if any) */
} xl_btree_vacuum;
-#define SizeOfBtreeVacuum (offsetof(xl_btree_vacuum, lastBlockVacuumed) + sizeof(BlockNumber))
+#define SizeOfBtreeVacuum (offsetof(xl_btree_vacuum, ndeleted) + sizeof(BlockNumber))
/*
* This is what we need to know about marking an empty branch for deletion.
diff --git a/src/tools/valgrind.supp b/src/tools/valgrind.supp
index ec47a22..71a03e3 100644
--- a/src/tools/valgrind.supp
+++ b/src/tools/valgrind.supp
@@ -212,3 +212,24 @@
Memcheck:Cond
fun:PyObject_Realloc
}
+
+# Temporarily work around bug in datum_image_eq's handling of the cstring
+# (typLen == -2) case. datumIsEqual() is not affected, but also doesn't handle
+# TOAST'ed values correctly.
+#
+# FIXME: Remove both suppressions when bug is fixed on master branch
+{
+ temporary_workaround_1
+ Memcheck:Addr1
+ fun:bcmp
+ fun:datum_image_eq
+ fun:_bt_keep_natts_fast
+}
+
+{
+ temporary_workaround_8
+ Memcheck:Addr8
+ fun:bcmp
+ fun:datum_image_eq
+ fun:_bt_keep_natts_fast
+}