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Commit9fc24f2

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Fix EXPLAIN ANALYZE bug noted by Wiebe Cazemier: although we were
properly advancing the CommandCounter between multiple sub-queriesgenerated by rules, we forgot to update the snapshot being used, sothat the successive sub-queries didn't actually see each others'results. This is still not *exactly* like the semantics of normalexecution of the same queries, in that we don't take new transactionsnapshots and hence don't see changes from concurrently committedcommands, but I think that's OK and probably even preferable forEXPLAIN ANALYZE.
1 parentef3b7cd commit9fc24f2

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2 files changed

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lines changed

2 files changed

+20
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lines changed

‎src/backend/commands/explain.c‎

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
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* Portions Copyright (c) 1994-5, Regents of the University of California
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.138 2005/10/15 02:49:15 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.139 2005/10/21 16:43:33 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -196,6 +196,15 @@ ExplainOneQuery(Query *query, ExplainStmt *stmt, TupOutputState *tstate)
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/* plan the query */
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plan=planner(query,isCursor,cursorOptions,NULL);
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/*
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* Update snapshot command ID to ensure this query sees results of any
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* previously executed queries. (It's a bit cheesy to modify
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* ActiveSnapshot without making a copy, but for the limited ways in
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* which EXPLAIN can be invoked, I think it's OK, because the active
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* snapshot shouldn't be shared with anything else anyway.)
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*/
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ActiveSnapshot->curcid=GetCurrentCommandId();
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/* Create a QueryDesc requesting no output */
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queryDesc=CreateQueryDesc(query,plan,
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ActiveSnapshot,InvalidSnapshot,

‎src/backend/commands/prepare.c‎

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
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* Copyright (c) 2002-2005, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.41 2005/10/15 02:49:15 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.42 2005/10/21 16:43:33 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -605,6 +605,15 @@ ExplainExecuteQuery(ExplainStmt *stmt, TupOutputState *tstate)
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query->into=execstmt->into;
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}
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/*
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* Update snapshot command ID to ensure this query sees results of
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* any previously executed queries. (It's a bit cheesy to modify
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* ActiveSnapshot without making a copy, but for the limited ways
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* in which EXPLAIN can be invoked, I think it's OK, because the
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* active snapshot shouldn't be shared with anything else anyway.)
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*/
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ActiveSnapshot->curcid=GetCurrentCommandId();
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/* Create a QueryDesc requesting no output */
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qdesc=CreateQueryDesc(query,plan,
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ActiveSnapshot,InvalidSnapshot,

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