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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2004-09-13 20:10:13 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2004-09-13 20:10:13 +0000 |
| commit | b2c4071299e02ed96d48d3c8e776de2fab36f88c (patch) | |
| tree | ff0db14826870f1c3fe46d94ea3a1e1697c658a7 /src/backend/access/transam/xact.c | |
| parent | d69528881ab72eac5a9f154f23dbf549789c264d (diff) | |
| download | postgresql-b2c4071299e02ed96d48d3c8e776de2fab36f88c.tar.gz postgresql-b2c4071299e02ed96d48d3c8e776de2fab36f88c.zip | |
Redesign query-snapshot timing so that volatile functions in READ COMMITTED
mode see a fresh snapshot for each command in the function, rather than
using the latest interactive command's snapshot. Also, suppress fresh
snapshots as well as CommandCounterIncrement inside STABLE and IMMUTABLE
functions, instead using the snapshot taken for the most closely nested
regular query. (This behavior is only sane for read-only functions, so
the patch also enforces that such functions contain only SELECT commands.)
As per my proposal of 6-Sep-2004; I note that I floated essentially the
same proposal on 19-Jun-2002, but that discussion tailed off without any
action. Since 8.0 seems like the right place to be taking possibly
nontrivial backwards compatibility hits, let's get it done now.
Diffstat (limited to 'src/backend/access/transam/xact.c')
| -rw-r--r-- | src/backend/access/transam/xact.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index 47c501c393e..ffcc324eb3e 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.187 2004/09/10 18:39:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.188 2004/09/13 20:06:04 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -401,11 +401,11 @@ CommandCounterIncrement(void) (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("cannot have more than 2^32-1 commands in a transaction"))); - /* Propagate new command ID into query snapshots, if set */ - if (QuerySnapshot) - QuerySnapshot->curcid = s->commandId; + /* Propagate new command ID into static snapshots, if set */ if (SerializableSnapshot) SerializableSnapshot->curcid = s->commandId; + if (LatestSnapshot) + LatestSnapshot->curcid = s->commandId; /* * make cache changes visible to me. @@ -3001,8 +3001,10 @@ CommitSubTransaction(void) s->state = TRANS_COMMIT; - /* Mark subtransaction as subcommitted */ + /* Must CCI to ensure commands of subtransaction are seen as done */ CommandCounterIncrement(); + + /* Mark subtransaction as subcommitted */ RecordSubTransactionCommit(); AtSubCommit_childXids(); |