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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2010-07-29 19:23:51 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2010-07-29 19:23:51 +0000 |
| commit | a0ad1d1f831d92e9bd94f6e821cc6c85804272e5 (patch) | |
| tree | 29b4bb581b65ce106f5fa4e229196195587d6acd | |
| parent | fb28d2604a419c48b0f6f8df46198a90d8343209 (diff) | |
| download | postgresql-a0ad1d1f831d92e9bd94f6e821cc6c85804272e5.tar.gz postgresql-a0ad1d1f831d92e9bd94f6e821cc6c85804272e5.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.
| -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 ec9696e6bbe..48bd6fa4419 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 1.206.2.10 2010/07/29 16:15:18 rhaas Exp $ + * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.206.2.11 2010/07/29 19:23:51 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -6095,11 +6095,11 @@ static void copy_relation_data(Relation rel, SMgrRelation dst) { SMgrRelation src; + char *buf; + Page page; bool use_wal; BlockNumber nblocks; BlockNumber blkno; - char buf[BLCKSZ]; - Page page = (Page) buf; /* * Since we copy the file directly without looking at the shared buffers, @@ -6110,6 +6110,15 @@ copy_relation_data(Relation rel, SMgrRelation dst) FlushRelationBuffers(rel); /* + * 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 PageSetLSN fail. + */ + buf = (char *) palloc(BLCKSZ); + page = (Page) buf; + + /* * We need to log the copied data in WAL iff WAL archiving is enabled AND * it's not a temp rel. */ @@ -6172,6 +6181,8 @@ copy_relation_data(Relation rel, SMgrRelation dst) smgrwrite(dst, 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 |