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Add an EXPLAIN (BUFFERS) option to show buffer-usage statistics.

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This patch also removes buffer-usage statistics from the track_counts
output, since this (or the global server statistics) is deemed to be a better
interface to this information.

Itagaki Takahiro, reviewed by Euler Taveira de Oliveira.
This commit is contained in:
Robert Haas
2009-12-15 04:57:48 +00:00
parent 6f1bf75d50
commit cddca5ec13
25 changed files with 274 additions and 140 deletions
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95
src/backend/commands/explain.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.195 2009/12/12 00:35:33 rhaas Exp $
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.196 2009/12/15 04:57:47 rhaas Exp $
*
*-------------------------------------------------------------------------
*/
@ -125,6 +125,8 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
es.verbose = defGetBoolean(opt);
else if (strcmp(opt->defname, "costs") == 0)
es.costs = defGetBoolean(opt);
else if (strcmp(opt->defname, "buffers") == 0)
es.buffers = defGetBoolean(opt);
else if (strcmp(opt->defname, "format") == 0)
{
char *p = defGetString(opt);
@ -150,6 +152,11 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
opt->defname)));
}
if (es.buffers && !es.analyze)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("EXPLAIN option BUFFERS requires ANALYZE")));
/*
* Run parse analysis and rewrite. Note this also acquires sufficient
* locks on the source table(s).
@ -339,6 +346,12 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainState *es,
instr_time starttime;
double totaltime = 0;
int eflags;
int instrument_option = 0;
if (es->analyze)
instrument_option |= INSTRUMENT_TIMER;
if (es->buffers)
instrument_option |= INSTRUMENT_BUFFERS;
/*
* Use a snapshot with an updated command ID to ensure this query sees
@ -349,7 +362,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainState *es,
/* Create a QueryDesc requesting no output */
queryDesc = CreateQueryDesc(plannedstmt, queryString,
GetActiveSnapshot(), InvalidSnapshot,
None_Receiver, params, es->analyze);
None_Receiver, params, instrument_option);
INSTR_TIME_SET_CURRENT(starttime);
@ -1042,6 +1055,84 @@ ExplainNode(Plan *plan, PlanState *planstate,
break;
}
/* Show buffer usage */
if (es->buffers)
{
const BufferUsage *usage = &planstate->instrument->bufusage;
if (es->format == EXPLAIN_FORMAT_TEXT)
{
bool has_shared = (usage->shared_blks_hit > 0 ||
usage->shared_blks_read > 0 ||
usage->shared_blks_written);
bool has_local = (usage->local_blks_hit > 0 ||
usage->local_blks_read > 0 ||
usage->local_blks_written);
bool has_temp = (usage->temp_blks_read > 0 ||
usage->temp_blks_written);
/* Show only positive counter values. */
if (has_shared || has_local || has_temp)
{
appendStringInfoSpaces(es->str, es->indent * 2);
appendStringInfoString(es->str, "Buffers:");
if (has_shared)
{
appendStringInfoString(es->str, " shared");
if (usage->shared_blks_hit > 0)
appendStringInfo(es->str, " hit=%ld",
usage->shared_blks_hit);
if (usage->shared_blks_read > 0)
appendStringInfo(es->str, " read=%ld",
usage->shared_blks_read);
if (usage->shared_blks_written > 0)
appendStringInfo(es->str, " written=%ld",
usage->shared_blks_written);
if (has_local || has_temp)
appendStringInfoChar(es->str, ',');
}
if (has_local)
{
appendStringInfoString(es->str, " local");
if (usage->local_blks_hit > 0)
appendStringInfo(es->str, " hit=%ld",
usage->local_blks_hit);
if (usage->local_blks_read > 0)
appendStringInfo(es->str, " read=%ld",
usage->local_blks_read);
if (usage->local_blks_written > 0)
appendStringInfo(es->str, " written=%ld",
usage->local_blks_written);
if (has_temp)
appendStringInfoChar(es->str, ',');
}
if (has_temp)
{
appendStringInfoString(es->str, " temp");
if (usage->temp_blks_read > 0)
appendStringInfo(es->str, " read=%ld",
usage->temp_blks_read);
if (usage->temp_blks_written > 0)
appendStringInfo(es->str, " written=%ld",
usage->temp_blks_written);
}
appendStringInfoChar(es->str, '\n');
}
}
else
{
ExplainPropertyLong("Shared Hit Blocks", usage->shared_blks_hit, es);
ExplainPropertyLong("Shared Read Blocks", usage->shared_blks_read, es);
ExplainPropertyLong("Shared Written Blocks", usage->shared_blks_written, es);
ExplainPropertyLong("Local Hit Blocks", usage->local_blks_hit, es);
ExplainPropertyLong("Local Read Blocks", usage->local_blks_read, es);
ExplainPropertyLong("Local Written Blocks", usage->local_blks_written, es);
ExplainPropertyLong("Temp Read Blocks", usage->temp_blks_read, es);
ExplainPropertyLong("Temp Written Blocks", usage->temp_blks_written, es);
}
}
/* Get ready to display the child plans */
haschildren = plan->initPlan ||
outerPlan(plan) ||