ssi-fast-bailout.patch
text/x-diff
Filename: ssi-fast-bailout.patch
Type: text/x-diff
Part: 0
Patch
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API reference →
Format: unified
| File | + | − |
|---|---|---|
| src/backend/storage/lmgr/predicate.c | 21 | 0 |
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index f02d5d5..48ff9cc 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -2275,6 +2275,18 @@ PredicateLockTupleRowVersionLink(const Relation relation, TransactionId oldxmin, newxmin; + /* + * Bail out quickly if there are no serializable transactions + * running. + * + * It's safe to do this check without taking any additional + * locks. Even if a serializable transaction starts concurrently, + * we know it can't take any SIREAD locks on the modified tuple + * because the caller is holding the associated buffer page lock. + */ + if (!TransactionIdIsValid(PredXact->SxactGlobalXmin)) + return; + oldblk = ItemPointerGetBlockNumber(&(oldTuple->t_self)); oldoff = ItemPointerGetOffsetNumber(&(oldTuple->t_self)); oldxmin = HeapTupleHeaderGetXmin(oldTuple->t_data); @@ -2633,6 +2645,15 @@ PredicateLockPageSplit(const Relation relation, const BlockNumber oldblkno, PREDICATELOCKTARGETTAG newtargettag; bool success; + /* + * Bail out quickly if there are no serializable transactions + * running. As with PredicateLockTupleRowVersionLink, it's safe to + * check this without taking locks because the caller is holding + * the buffer page lock. + */ + if (!TransactionIdIsValid(PredXact->SxactGlobalXmin)) + return; + if (SkipSplitTracking(relation)) return;