From 45ba97a206a8c8f04188fe10b9b73c0b79f5d263 Mon Sep 17 00:00:00 2001 From: Ashwin Agrawal Date: Fri, 2 Aug 2019 15:21:16 -0700 Subject: [PATCH v1 2/3] Optimize PredicateLockTuple(). PredicateLockTuple fast exits if tuple was written by current transaction, as for that case it already has the lock. This check can be easily performed using TransactionIdIsCurrentTransactionId() instead of using SubTransGetTopmostTransaction(). Since TransactionIdIsCurrentTransactionId() is all in-memory operation, makes this efficient compared to SubTransGetTopmostTransaction(), which can hit the disk. This simplification was proposed by Andres. --- src/backend/storage/lmgr/predicate.c | 22 ++++------------------ 1 file changed, 4 insertions(+), 18 deletions(-) diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index 2d709420c3d..1417ba37441 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -2559,24 +2559,10 @@ PredicateLockTuple(Relation relation, HeapTuple tuple, Snapshot snapshot) */ if (relation->rd_index == NULL) { - TransactionId myxid; - - targetxmin = HeapTupleHeaderGetXmin(tuple->t_data); - - myxid = GetTopTransactionIdIfAny(); - if (TransactionIdIsValid(myxid)) - { - if (TransactionIdFollowsOrEquals(targetxmin, TransactionXmin)) - { - TransactionId xid = SubTransGetTopmostTransaction(targetxmin); - - if (TransactionIdEquals(xid, myxid)) - { - /* We wrote it; we already have a write lock. */ - return; - } - } - } + /* If we wrote it; we already have a write lock. */ + if (TransactionIdIsCurrentTransactionId( + HeapTupleHeaderGetXmin(tuple->t_data))) + return; } /* -- 2.19.1