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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/commands/explain.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/commands/explain.c')
| -rw-r--r-- | src/backend/commands/explain.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 9b7cf1ae491..f51b991b4d0 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1994-5, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.125 2004/09/10 18:39:56 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.126 2004/09/13 20:06:28 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -180,7 +180,9 @@ ExplainOneQuery(Query *query, ExplainStmt *stmt, TupOutputState *tstate) plan = planner(query, isCursor, cursorOptions, NULL); /* Create a QueryDesc requesting no output */ - queryDesc = CreateQueryDesc(query, plan, None_Receiver, NULL, + queryDesc = CreateQueryDesc(query, plan, + ActiveSnapshot, InvalidSnapshot, + None_Receiver, NULL, stmt->analyze); ExplainOnePlan(queryDesc, stmt, tstate); @@ -212,7 +214,7 @@ ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt, AfterTriggerBeginQuery(); /* call ExecutorStart to prepare the plan for execution */ - ExecutorStart(queryDesc, false, !stmt->analyze); + ExecutorStart(queryDesc, !stmt->analyze); /* Execute the plan for statistics if asked for */ if (stmt->analyze) @@ -272,7 +274,9 @@ ExplainOnePlan(QueryDesc *queryDesc, ExplainStmt *stmt, FreeQueryDesc(queryDesc); - CommandCounterIncrement(); + /* We need a CCI just in case query expanded to multiple plans */ + if (stmt->analyze) + CommandCounterIncrement(); totaltime += elapsed_time(&starttime); |