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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2010-07-29 19:23:37 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2010-07-29 19:23:37 +0000 |
| commit | b08fd11508a2b36e64f456d8e0345f1c66dae333 (patch) | |
| tree | 05f32934ec1106fbba8c6d4b1761b253d29cbb0d /src | |
| parent | 2d8346182f5cbf743aa2a807893291d74321f8c0 (diff) | |
| download | postgresql-b08fd11508a2b36e64f456d8e0345f1c66dae333.tar.gz postgresql-b08fd11508a2b36e64f456d8e0345f1c66dae333.zip | |
Fix another longstanding problem in copy_relation_data: it was blithely
assuming that a local char[] array would be aligned on at least a word
boundary. There are architectures on which that is pretty much guaranteed to
NOT be the case ... and those arches also don't like non-aligned memory
accesses, meaning that log_newpage() would crash if it ever got invoked.
Even on Intel-ish machines there's a potential for a large performance penalty
from doing I/O to an inadequately aligned buffer. So palloc it instead.
Backpatch to 8.0 --- 7.4 doesn't have this code.
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/commands/tablecmds.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 3a899125a62..d07e51fb658 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.288.2.4 2010/07/01 14:12:04 rhaas Exp $ + * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.288.2.5 2010/07/29 19:23:37 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -6822,11 +6822,20 @@ static void copy_relation_data(SMgrRelation src, SMgrRelation dst, ForkNumber forkNum, bool istemp) { + char *buf; + Page page; bool use_wal; BlockNumber nblocks; BlockNumber blkno; - char buf[BLCKSZ]; - Page page = (Page) buf; + + /* + * palloc the buffer so that it's MAXALIGN'd. If it were just a local + * char[] array, the compiler might align it on any byte boundary, which + * can seriously hurt transfer speed to and from the kernel; not to + * mention possibly making log_newpage's accesses to the page header fail. + */ + buf = (char *) palloc(BLCKSZ); + page = (Page) buf; /* * We need to log the copied data in WAL iff WAL archiving is enabled AND @@ -6855,6 +6864,8 @@ copy_relation_data(SMgrRelation src, SMgrRelation dst, smgrextend(dst, forkNum, blkno, buf, true); } + pfree(buf); + /* * If the rel isn't temp, we must fsync it down to disk before it's safe * to commit the transaction. (For a temp rel we don't care since the rel |