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Some infrastructure changes for the upcoming auto-explain contrib module:
* Refactor explain.c slightly to export a convenient-to-use subroutine for printing EXPLAIN results. * Provide hooks for plugins to get control at ExecutorStart and ExecutorEnd as well as ExecutorRun. * Add some minimal support for tracking the total runtime of ExecutorRun. This code won't actually do anything unless a plugin prods it to. * Change the API of the DefineCustomXXXVariable functions to allow nonzero "flags" to be specified for a custom GUC variable. While at it, also make the "bootstrap" default value for custom GUCs be explicitly specified as a parameter to these functions. This is to eliminate confusion over where the default comes from, as has been expressed in the past by some users of the custom-variable facility. * Refactor GUC code a bit to ensure that a custom variable gets initialized to something valid (like its default value) even if the placeholder value was invalid.
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10 files changed

+293
-170
lines changed

10 files changed

+293
-170
lines changed

‎src/backend/commands/explain.c

Lines changed: 32 additions & 14 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994-5, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.180 2008/10/06 20:29:38 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.181 2008/11/19 01:10:23 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -224,7 +224,6 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
224224
QueryDesc *queryDesc;
225225
instr_time starttime;
226226
double totaltime = 0;
227-
ExplainState *es;
228227
StringInfoData buf;
229228
int eflags;
230229

@@ -265,17 +264,9 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
265264
totaltime += elapsed_time(&starttime);
266265
}
267266

268-
es = (ExplainState *) palloc0(sizeof(ExplainState));
269-
270-
es->printTList = stmt->verbose;
271-
es->printAnalyze = stmt->analyze;
272-
es->pstmt = queryDesc->plannedstmt;
273-
es->rtable = queryDesc->plannedstmt->rtable;
274-
267+
/* Create textual dump of plan tree */
275268
initStringInfo(&buf);
276-
explain_outNode(&buf,
277-
queryDesc->plannedstmt->planTree, queryDesc->planstate,
278-
NULL, 0, es);
269+
ExplainPrintPlan(&buf, queryDesc, stmt->analyze, stmt->verbose);
279270

280271
/*
281272
* If we ran the command, run any AFTER triggers it queued. (Note this
@@ -290,7 +281,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
290281
}
291282

292283
/* Print info about runtime of triggers */
293-
if (es->printAnalyze)
284+
if (stmt->analyze)
294285
{
295286
ResultRelInfo *rInfo;
296287
bool show_relname;
@@ -335,7 +326,34 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ParamListInfo params,
335326
do_text_output_multiline(tstate, buf.data);
336327

337328
pfree(buf.data);
338-
pfree(es);
329+
}
330+
331+
/*
332+
* ExplainPrintPlan -
333+
* convert a QueryDesc's plan tree to text and append it to 'str'
334+
*
335+
* 'analyze' means to include runtime instrumentation results
336+
* 'verbose' means a verbose printout (currently, it shows targetlists)
337+
*
338+
* NB: will not work on utility statements
339+
*/
340+
void
341+
ExplainPrintPlan(StringInfo str, QueryDesc *queryDesc,
342+
bool analyze, bool verbose)
343+
{
344+
ExplainState es;
345+
346+
Assert(queryDesc->plannedstmt != NULL);
347+
348+
memset(&es, 0, sizeof(es));
349+
es.printTList = verbose;
350+
es.printAnalyze = analyze;
351+
es.pstmt = queryDesc->plannedstmt;
352+
es.rtable = queryDesc->plannedstmt->rtable;
353+
354+
explain_outNode(str,
355+
queryDesc->plannedstmt->planTree, queryDesc->planstate,
356+
NULL, 0, &es);
339357
}
340358

341359
/*

‎src/backend/executor/execMain.c

Lines changed: 41 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -26,7 +26,7 @@
2626
*
2727
*
2828
* IDENTIFICATION
29-
* $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.317 2008/11/16 17:34:28 tgl Exp $
29+
* $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.318 2008/11/19 01:10:23 tgl Exp $
3030
*
3131
*-------------------------------------------------------------------------
3232
*/
@@ -60,8 +60,10 @@
6060
#include "utils/tqual.h"
6161

6262

63-
/* Hook for plugins to get control in ExecutorRun() */
64-
ExecutorRun_hook_type ExecutorRun_hook = NULL;
63+
/* Hooks for plugins to get control in ExecutorStart/Run/End() */
64+
ExecutorStart_hook_type ExecutorStart_hook = NULL;
65+
ExecutorRun_hook_type ExecutorRun_hook = NULL;
66+
ExecutorEnd_hook_type ExecutorEnd_hook = NULL;
6567

6668
typedef struct evalPlanQual
6769
{
@@ -129,10 +131,24 @@ static void intorel_destroy(DestReceiver *self);
129131
*
130132
* NB: the CurrentMemoryContext when this is called will become the parent
131133
* of the per-query context used for this Executor invocation.
134+
*
135+
* We provide a function hook variable that lets loadable plugins
136+
* get control when ExecutorStart is called. Such a plugin would
137+
* normally call standard_ExecutorStart().
138+
*
132139
* ----------------------------------------------------------------
133140
*/
134141
void
135142
ExecutorStart(QueryDesc *queryDesc, int eflags)
143+
{
144+
if (ExecutorStart_hook)
145+
(*ExecutorStart_hook) (queryDesc, eflags);
146+
else
147+
standard_ExecutorStart(queryDesc, eflags);
148+
}
149+
150+
void
151+
standard_ExecutorStart(QueryDesc *queryDesc, int eflags)
136152
{
137153
EState *estate;
138154
MemoryContext oldcontext;
@@ -263,6 +279,10 @@ standard_ExecutorRun(QueryDesc *queryDesc,
263279
*/
264280
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
265281

282+
/* Allow instrumentation of ExecutorRun overall runtime */
283+
if (queryDesc->totaltime)
284+
InstrStartNode(queryDesc->totaltime);
285+
266286
/*
267287
* extract information from the query descriptor and the query feature.
268288
*/
@@ -298,6 +318,9 @@ standard_ExecutorRun(QueryDesc *queryDesc,
298318
if (sendTuples)
299319
(*dest->rShutdown) (dest);
300320

321+
if (queryDesc->totaltime)
322+
InstrStopNode(queryDesc->totaltime, estate->es_processed);
323+
301324
MemoryContextSwitchTo(oldcontext);
302325
}
303326

@@ -306,10 +329,24 @@ standard_ExecutorRun(QueryDesc *queryDesc,
306329
*
307330
* This routine must be called at the end of execution of any
308331
* query plan
332+
*
333+
* We provide a function hook variable that lets loadable plugins
334+
* get control when ExecutorEnd is called. Such a plugin would
335+
* normally call standard_ExecutorEnd().
336+
*
309337
* ----------------------------------------------------------------
310338
*/
311339
void
312340
ExecutorEnd(QueryDesc *queryDesc)
341+
{
342+
if (ExecutorEnd_hook)
343+
(*ExecutorEnd_hook) (queryDesc);
344+
else
345+
standard_ExecutorEnd(queryDesc);
346+
}
347+
348+
void
349+
standard_ExecutorEnd(QueryDesc *queryDesc)
313350
{
314351
EState *estate;
315352
MemoryContext oldcontext;
@@ -353,6 +390,7 @@ ExecutorEnd(QueryDesc *queryDesc)
353390
queryDesc->tupDesc = NULL;
354391
queryDesc->estate = NULL;
355392
queryDesc->planstate = NULL;
393+
queryDesc->totaltime = NULL;
356394
}
357395

358396
/* ----------------------------------------------------------------

‎src/backend/tcop/pquery.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.124 2008/08/01 13:16:09 alvherre Exp $
11+
* $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.125 2008/11/19 01:10:23 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -82,6 +82,7 @@ CreateQueryDesc(PlannedStmt *plannedstmt,
8282
qd->tupDesc = NULL;
8383
qd->estate = NULL;
8484
qd->planstate = NULL;
85+
qd->totaltime = NULL;
8586

8687
return qd;
8788
}
@@ -110,6 +111,7 @@ CreateUtilityQueryDesc(Node *utilitystmt,
110111
qd->tupDesc = NULL;
111112
qd->estate = NULL;
112113
qd->planstate = NULL;
114+
qd->totaltime = NULL;
113115

114116
return qd;
115117
}

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