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Add the option to report WAL usage in EXPLAIN and auto_explain.

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This commit adds a new option WAL similar to existing option BUFFERS in the
EXPLAIN command.  This option allows to include information on WAL record
generation added by commit df3b181499 in EXPLAIN output.

This also allows the WAL usage information to be displayed via
the auto_explain module.  A new parameter auto_explain.log_wal controls
whether WAL usage statistics are printed when an execution plan is logged.
This parameter has no effect unless auto_explain.log_analyze is enabled.

Author: Julien Rouhaud
Reviewed-by: Dilip Kumar and Amit Kapila
Discussion: https://postgr.es/m/CAB-hujrP8ZfUkvL5OYETipQwA=e3n7oqHFU=4ZLxWS_Cza3kQQ@mail.gmail.com
This commit is contained in:
Amit Kapila
2020-04-06 08:02:15 +05:30
parent a40caf5f86
commit 33e05f89c5
6 changed files with 124 additions and 6 deletions
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74
src/backend/commands/explain.c
View File

@ -113,6 +113,7 @@ static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
static const char *explain_get_index_name(Oid indexId);
static void show_buffer_usage(ExplainState *es, const BufferUsage *usage);
static void show_wal_usage(ExplainState *es, const WalUsage *usage);
static void ExplainIndexScanDetails(Oid indexid, ScanDirection indexorderdir,
ExplainState *es);
static void ExplainScanTarget(Scan *plan, ExplainState *es);
@ -175,6 +176,8 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
es->costs = defGetBoolean(opt);
else if (strcmp(opt->defname, "buffers") == 0)
es->buffers = defGetBoolean(opt);
else if (strcmp(opt->defname, "wal") == 0)
es->wal = defGetBoolean(opt);
else if (strcmp(opt->defname, "settings") == 0)
es->settings = defGetBoolean(opt);
else if (strcmp(opt->defname, "timing") == 0)
@ -219,6 +222,11 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("EXPLAIN option BUFFERS requires ANALYZE")));
if (es->wal && !es->analyze)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("EXPLAIN option WAL requires ANALYZE")));
/* if the timing was not set explicitly, set default value */
es->timing = (timing_set) ? es->timing : es->analyze;
@ -506,6 +514,8 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
if (es->buffers)
instrument_option |= INSTRUMENT_BUFFERS;
if (es->wal)
instrument_option |= INSTRUMENT_WAL;
/*
* We always collect timing for the entire statement, even when node-level
@ -1970,12 +1980,14 @@ ExplainNode(PlanState *planstate, List *ancestors,
}
}
/* Show buffer usage */
/* Show buffer/WAL usage */
if (es->buffers && planstate->instrument)
show_buffer_usage(es, &planstate->instrument->bufusage);
if (es->wal && planstate->instrument)
show_wal_usage(es, &planstate->instrument->walusage);
/* Prepare per-worker buffer usage */
if (es->workers_state && es->buffers && es->verbose)
/* Prepare per-worker buffer/WAL usage */
if (es->workers_state && (es->buffers || es->wal) && es->verbose)
{
WorkerInstrumentation *w = planstate->worker_instrument;
@ -1988,7 +2000,10 @@ ExplainNode(PlanState *planstate, List *ancestors,
continue;
ExplainOpenWorker(n, es);
show_buffer_usage(es, &instrument->bufusage);
if (es->buffers)
show_buffer_usage(es, &instrument->bufusage);
if (es->wal)
show_wal_usage(es, &instrument->walusage);
ExplainCloseWorker(n, es);
}
}
@ -3087,6 +3102,44 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage)
}
}
/*
* Show WAL usage details.
*/
static void
show_wal_usage(ExplainState *es, const WalUsage *usage)
{
if (es->format == EXPLAIN_FORMAT_TEXT)
{
/* Show only positive counter values. */
if ((usage->wal_records > 0) || (usage->wal_num_fpw > 0) ||
(usage->wal_bytes > 0))
{
ExplainIndentText(es);
appendStringInfoString(es->str, "WAL:");
if (usage->wal_records > 0)
appendStringInfo(es->str, " records=%ld",
usage->wal_records);
if (usage->wal_num_fpw > 0)
appendStringInfo(es->str, " full page writes=%ld",
usage->wal_num_fpw);
if (usage->wal_bytes > 0)
appendStringInfo(es->str, " bytes=" UINT64_FORMAT,
usage->wal_bytes);
appendStringInfoChar(es->str, '\n');
}
}
else
{
ExplainPropertyInteger("WAL records", NULL,
usage->wal_records, es);
ExplainPropertyInteger("WAL full page writes", NULL,
usage->wal_num_fpw, es);
ExplainPropertyUInteger("WAL bytes", NULL,
usage->wal_bytes, es);
}
}
/*
* Add some additional details about an IndexScan or IndexOnlyScan
*/
@ -3871,6 +3924,19 @@ ExplainPropertyInteger(const char *qlabel, const char *unit, int64 value,
ExplainProperty(qlabel, unit, buf, true, es);
}
/*
* Explain an unsigned integer-valued property.
*/
void
ExplainPropertyUInteger(const char *qlabel, const char *unit, uint64 value,
ExplainState *es)
{
char buf[32];
snprintf(buf, sizeof(buf), UINT64_FORMAT, value);
ExplainProperty(qlabel, unit, buf, true, es);
}
/*
* Explain a float-valued property, using the specified number of
* fractional digits.