From 703d123ffd0a35d11e67b4cb07ceaeca1a527425 Mon Sep 17 00:00:00 2001 From: Ashwin Agrawal Date: Fri, 2 Aug 2019 15:21:16 -0700 Subject: [PATCH v2 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 85a629f4fce..f4d8c2528a1 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