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Include information on buffer usage during planning phase, in EXPLAIN output.

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When BUFFERS option is enabled, EXPLAIN command includes the information
on buffer usage during each plan node, in its output. In addition to that,
this commit makes EXPLAIN command include also the information on
buffer usage during planning phase, in its output. This feature makes it
easier to discern the cases where lots of buffer access happen during
planning.

Author: Julien Rouhaud, slightly revised by Fujii Masao
Reviewed-by: Justin Pryzby
Discussion: https://postgr.es/m/16109-26a1a88651e90608@postgresql.org
This commit is contained in:
Fujii Masao
2020-04-03 11:27:09 +09:00
parent ac44367efb
commit ed7a509571
4 changed files with 95 additions and 8 deletions
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32
src/backend/commands/explain.c
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@ -372,7 +372,11 @@ ExplainOneQuery(Query *query, int cursorOptions,
PlannedStmt *plan;
instr_time planstart,
planduration;
BufferUsage bufusage_start,
bufusage;
if (es->buffers)
bufusage_start = pgBufferUsage;
INSTR_TIME_SET_CURRENT(planstart);
/* plan the query */
@ -381,9 +385,16 @@ ExplainOneQuery(Query *query, int cursorOptions,
INSTR_TIME_SET_CURRENT(planduration);
INSTR_TIME_SUBTRACT(planduration, planstart);
/* calc differences of buffer counters. */
if (es->buffers)
{
memset(&bufusage, 0, sizeof(BufferUsage));
BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start);
}
/* run it (if needed) and produce output */
ExplainOnePlan(plan, into, es, queryString, params, queryEnv,
&planduration);
&planduration, (es->buffers ? &bufusage : NULL));
}
}
@ -476,7 +487,8 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
void
ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
const char *queryString, ParamListInfo params,
QueryEnvironment *queryEnv, const instr_time *planduration)
QueryEnvironment *queryEnv, const instr_time *planduration,
const BufferUsage *bufusage)
{
DestReceiver *dest;
QueryDesc *queryDesc;
@ -560,6 +572,9 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
/* Create textual dump of plan tree */
ExplainPrintPlan(es, queryDesc);
if (es->summary && (planduration || bufusage))
ExplainOpenGroup("Planning", "Planning", true, es);
if (es->summary && planduration)
{
double plantime = INSTR_TIME_GET_DOUBLE(*planduration);
@ -567,6 +582,19 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
ExplainPropertyFloat("Planning Time", "ms", 1000.0 * plantime, 3, es);
}
/* Show buffer usage */
if (es->summary && bufusage)
{
if (es->format == EXPLAIN_FORMAT_TEXT)
es->indent++;
show_buffer_usage(es, bufusage);
if (es->format == EXPLAIN_FORMAT_TEXT)
es->indent--;
}
if (es->summary && (planduration || bufusage))
ExplainCloseGroup("Planning", "Planning", true, es);
/* Print info about runtime of triggers */
if (es->analyze)
ExplainPrintTriggers(es, queryDesc);