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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2010-07-29 19:23:58 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2010-07-29 19:23:58 +0000 |
| commit | 9e468f94aa30cef7c188a2b8b0d26f26130d44c0 (patch) | |
| tree | 0a9bffdfbceab3625af4a2391867a784374f7a8a | |
| parent | 76a106f264b78b35b4f522e07cca84b90af83f50 (diff) | |
| download | postgresql-9e468f94aa30cef7c188a2b8b0d26f26130d44c0.tar.gz postgresql-9e468f94aa30cef7c188a2b8b0d26f26130d44c0.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 8f8d28e825c..3d2e385b088 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 1.174.2.11 2010/07/29 16:15:33 rhaas Exp $ + * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.174.2.12 2010/07/29 19:23:58 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -5837,11 +5837,11 @@ 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, @@ -5852,6 +5852,15 @@ 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. */ @@ -5914,6 +5923,8 @@ 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 |