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

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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
This commit is contained in:
Andres Freund 2023-03-22 09:26:23 -07:00
parent a70e6e4306
commit 560bb56c6e
1 changed files with 4 additions and 3 deletions
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7
src/backend/storage/buffer/bufmgr.c
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@ -3756,11 +3756,9 @@ RelationCopyStorageUsingBuffer(RelFileNode srcnode,
LockBuffer(srcBuf, BUFFER_LOCK_SHARE);
srcPage = BufferGetPage(srcBuf);
/* Use P_NEW to extend the destination relation. */
dstBuf = ReadBufferWithoutRelcache(dstnode, forkNum, blkno,
RBM_NORMAL, bstrategy_dst,
RBM_ZERO_AND_LOCK, bstrategy_dst,
permanent);
LockBuffer(dstBuf, BUFFER_LOCK_EXCLUSIVE);
dstPage = BufferGetPage(dstBuf);
START_CRIT_SECTION();
@ -3778,6 +3776,9 @@ RelationCopyStorageUsingBuffer(RelFileNode srcnode,
UnlockReleaseBuffer(dstBuf);
UnlockReleaseBuffer(srcBuf);
}
FreeAccessStrategy(bstrategy_src);
FreeAccessStrategy(bstrategy_dst);
}
/* ---------------------------------------------------------------------