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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2009-03-31 22:12:48 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2009-03-31 22:12:48 +0000 |
| commit | 948d6ec90fd35d6e1a59d0b1af8d6efd8442f0ad (patch) | |
| tree | c9184787540c4daa3ae880ea8969d77140a40a5b /src/backend/storage/buffer/bufmgr.c | |
| parent | 84a059abf75019f56eba51f33f90b018df8c1116 (diff) | |
| download | postgresql-948d6ec90fd35d6e1a59d0b1af8d6efd8442f0ad.tar.gz postgresql-948d6ec90fd35d6e1a59d0b1af8d6efd8442f0ad.zip | |
Modify the relcache to record the temp status of both local and nonlocal
temp relations; this is no more expensive than before, now that we have
pg_class.relistemp. Insert tests into bufmgr.c to prevent attempting
to fetch pages from nonlocal temp relations. This provides a low-level
defense against bugs-of-omission allowing temp pages to be loaded into shared
buffers, as in the contrib/pgstattuple problem reported by Stuart Bishop.
While at it, tweak a bunch of places to use new relcache tests (instead of
expensive probes into pg_namespace) to detect local or nonlocal temp tables.
Diffstat (limited to 'src/backend/storage/buffer/bufmgr.c')
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 1f6e8d36803..4a7dda3edbb 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.249 2009/03/23 01:52:38 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/storage/buffer/bufmgr.c,v 1.250 2009/03/31 22:12:48 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -122,6 +122,12 @@ PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum) if (reln->rd_istemp) { + /* see comments in ReadBufferExtended */ + if (RELATION_IS_OTHER_TEMP(reln)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary tables of other sessions"))); + /* pass it off to localbuf.c */ LocalPrefetchBuffer(reln->rd_smgr, forkNum, blockNum); } @@ -205,6 +211,16 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum, RelationOpenSmgr(reln); /* + * Reject attempts to read non-local temporary relations; we would + * be likely to get wrong data since we have no visibility into the + * owning session's local buffers. + */ + if (RELATION_IS_OTHER_TEMP(reln)) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary tables of other sessions"))); + + /* * Read the buffer, and update pgstat counters to reflect a cache * hit or miss. */ @@ -220,6 +236,8 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum, /* * ReadBufferWithoutRelcache -- like ReadBufferExtended, but doesn't require * a relcache entry for the relation. + * + * NB: caller is assumed to know what it's doing if isTemp is true. */ Buffer ReadBufferWithoutRelcache(RelFileNode rnode, bool isTemp, |