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Fix memory leak and inefficiency in CREATE DATABASE ... STRATEGY WAL_LOG

author Andres Freund <andres@anarazel.de>

2023年3月21日 04:57:40 +0000 (21:57 -0700)

committer Andres Freund <andres@anarazel.de>

2023年3月22日 16:20:34 +0000 (09:20 -0700)

RelationCopyStorageUsingBuffer() did not free the strategies used to access
the source / target relation. They memory was released at the end of the
transaction, but when using a template database with a lot of relations, the
temporary leak can become big prohibitively big.

RelationCopyStorageUsingBuffer() acquired the buffer for the target relation
with RBM_NORMAL, therefore requiring a read of a block guaranteed to be
zero. Use RBM_ZERO_AND_LOCK instead.

Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://postgr.es/m/20230321070113.o2vqqxogjykwgfrr@awork3.anarazel.de
Backpatch: 15-, where STRATEGY WAL_LOG was introduced

src/backend/storage/buffer/bufmgr.c patch | blob | blame | history

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c

index 0a05577b68df21349fe1dc2a1018b2985e66dbb8..95212a39416eece3a448f12cb8f82dc53a9f78e7 100644 (file)

--- a/src/backend/storage/buffer/bufmgr.c

+++ b/src/backend/storage/buffer/bufmgr.c

@@ -3833,11 +3833,9 @@ RelationCopyStorageUsingBuffer(RelFileLocator srclocator,

LockBuffer(srcBuf, BUFFER_LOCK_SHARE);

srcPage = BufferGetPage(srcBuf);

- /* Use P_NEW to extend the destination relation. */

dstBuf = ReadBufferWithoutRelcache(dstlocator, forkNum, blkno,

- RBM_NORMAL, bstrategy_dst,

+ RBM_ZERO_AND_LOCK, bstrategy_dst,