From c3ae01de0ded48590995115065889f1613bf458f Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Fri, 21 Feb 2025 10:58:59 -0500 Subject: [PATCH v33 1/5] Add lossy indicator to TBMIterateResult TBMIterateResult->ntuples is -1 when the page in the bitmap is lossy. Add an explicit lossy indicator so that we can move ntuples out of the TBMIterateResult in a future commit. --- src/backend/access/gin/ginget.c | 6 ++++-- src/backend/access/heap/heapam_handler.c | 10 +++++----- src/backend/nodes/tidbitmap.c | 11 ++++++++--- src/include/nodes/tidbitmap.h | 5 +++-- 4 files changed, 20 insertions(+), 12 deletions(-) diff --git a/src/backend/access/gin/ginget.c b/src/backend/access/gin/ginget.c index 63dd1f3679f..54aecc1d1f1 100644 --- a/src/backend/access/gin/ginget.c +++ b/src/backend/access/gin/ginget.c @@ -827,7 +827,7 @@ entryGetItem(GinState *ginstate, GinScanEntry entry, * in the bitmap. */ while (entry->matchResult == NULL || - (entry->matchResult->ntuples >= 0 && + (!entry->matchResult->lossy && entry->offset >= entry->matchResult->ntuples) || entry->matchResult->blockno < advancePastBlk || (ItemPointerIsLossyPage(&advancePast) && @@ -860,7 +860,7 @@ entryGetItem(GinState *ginstate, GinScanEntry entry, * We're now on the first page after advancePast which has any * items on it. If it's a lossy result, return that. */ - if (entry->matchResult->ntuples < 0) + if (entry->matchResult->lossy) { ItemPointerSetLossyPage(&entry->curItem, entry->matchResult->blockno); @@ -879,6 +879,8 @@ entryGetItem(GinState *ginstate, GinScanEntry entry, */ if (entry->matchResult->blockno == advancePastBlk) { + Assert(entry->matchResult->ntuples > 0); + /* * First, do a quick check against the last offset on the * page. If that's > advancePast, so are all the other diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c index c0bec014154..269d581c2ec 100644 --- a/src/backend/access/heap/heapam_handler.c +++ b/src/backend/access/heap/heapam_handler.c @@ -2170,7 +2170,7 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, VM_ALL_VISIBLE(scan->rs_rd, tbmres->blockno, &bscan->rs_vmbuffer)) { /* can't be lossy in the skip_fetch case */ - Assert(tbmres->ntuples >= 0); + Assert(!tbmres->lossy); Assert(bscan->rs_empty_tuples_pending >= 0); bscan->rs_empty_tuples_pending += tbmres->ntuples; @@ -2207,7 +2207,7 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, /* * We need two separate strategies for lossy and non-lossy cases. */ - if (tbmres->ntuples >= 0) + if (!tbmres->lossy) { /* * Bitmap is non-lossy, so we just look through the offsets listed in @@ -2268,10 +2268,10 @@ heapam_scan_bitmap_next_block(TableScanDesc scan, Assert(ntup <= MaxHeapTuplesPerPage); hscan->rs_ntuples = ntup; - if (tbmres->ntuples >= 0) - (*exact_pages)++; - else + if (tbmres->lossy) (*lossy_pages)++; + else + (*exact_pages)++; /* * Return true to indicate that a valid block was found and the bitmap is diff --git a/src/backend/nodes/tidbitmap.c b/src/backend/nodes/tidbitmap.c index 66b3c387d53..3e0bca651f5 100644 --- a/src/backend/nodes/tidbitmap.c +++ b/src/backend/nodes/tidbitmap.c @@ -961,12 +961,13 @@ tbm_advance_schunkbit(PagetableEntry *chunk, int *schunkbitp) * * Returns a TBMIterateResult representing one page, or NULL if there are * no more pages to scan. Pages are guaranteed to be delivered in numerical - * order. If result->ntuples < 0, then the bitmap is "lossy" and failed to + * order. If lossy is true, then the bitmap is "lossy" and failed to * remember the exact tuples to look at on this page --- the caller must * examine all tuples on the page and check if they meet the intended - * condition. If result->recheck is true, only the indicated tuples need + * condition. result->ntuples is set to -1 when the bitmap is lossy. + * If result->recheck is true, only the indicated tuples need * be examined, but the condition must be rechecked anyway. (For ease of - * testing, recheck is always set true when ntuples < 0.) + * testing, recheck is always set true when lossy is true.) */ TBMIterateResult * tbm_private_iterate(TBMPrivateIterator *iterator) @@ -1012,6 +1013,7 @@ tbm_private_iterate(TBMPrivateIterator *iterator) /* Return a lossy page indicator from the chunk */ output->blockno = chunk_blockno; output->ntuples = -1; + output->lossy = true; output->recheck = true; iterator->schunkbit++; return output; @@ -1033,6 +1035,7 @@ tbm_private_iterate(TBMPrivateIterator *iterator) ntuples = tbm_extract_page_tuple(page, output); output->blockno = page->blockno; output->ntuples = ntuples; + output->lossy = false; output->recheck = page->recheck; iterator->spageptr++; return output; @@ -1105,6 +1108,7 @@ tbm_shared_iterate(TBMSharedIterator *iterator) /* Return a lossy page indicator from the chunk */ output->blockno = chunk_blockno; output->ntuples = -1; + output->lossy = true; output->recheck = true; istate->schunkbit++; @@ -1122,6 +1126,7 @@ tbm_shared_iterate(TBMSharedIterator *iterator) ntuples = tbm_extract_page_tuple(page, output); output->blockno = page->blockno; output->ntuples = ntuples; + output->lossy = false; output->recheck = page->recheck; istate->spageptr++; diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h index a6ffeac90be..8cd93d90a86 100644 --- a/src/include/nodes/tidbitmap.h +++ b/src/include/nodes/tidbitmap.h @@ -54,9 +54,10 @@ typedef struct TBMIterator typedef struct TBMIterateResult { BlockNumber blockno; /* page number containing tuples */ - int ntuples; /* -1 indicates lossy result */ + int ntuples; /* -1 when lossy */ + bool lossy; bool recheck; /* should the tuples be rechecked? */ - /* Note: recheck is always true if ntuples < 0 */ + /* Note: recheck is always true if lossy */ OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER]; } TBMIterateResult; -- 2.34.1