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Commit 674899a

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MasaoFujiiMasaoFujii
committed
Rework EXPLAIN for planner's buffer usage.
Commit ce77abe allowed EXPLAIN (BUFFERS) to report the information on buffer usage during planning phase. However three issues were reported regarding this feature. (1) Previously, EXPLAIN option BUFFERS required ANALYZE. So the query had to be actually executed by specifying ANALYZE even when we want to see only the planner's buffer usage. This was inconvenient especially when the query was write one like DELETE. (2) EXPLAIN included the planner's buffer usage in summary information. So SUMMARY option had to be enabled to report that. Also this format was confusing. (3) The output structure for planning information was not consistent between TEXT format and the others. For example, "Planning" tag was output in JSON format, but not in TEXT format. For (1), this commit allows us to perform EXPLAIN (BUFFERS) without ANALYZE to report the planner's buffer usage. For (2), this commit changed EXPLAIN output so that the planner's buffer usage is reported before summary information. For (3), this commit made the output structure for planning information more consistent between the formats. Back-patch to v13 where the planner's buffer usage was allowed to be reported in EXPLAIN. Reported-by: Pierre Giraud, David Rowley Author: Fujii Masao Reviewed-by: David Rowley, Julien Rouhaud, Pierre Giraud Discussion: https://postgr.es/m/07b226e6-fa49-687f-b110-b7c37572f69e@dalibo.com
1 parent 0d7437d commit 674899a

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4 files changed

+77
-29
lines changed

4 files changed

+77
-29
lines changed

‎doc/src/sgml/ref/explain.sgml

+1-2
Original file line numberDiff line numberDiff line change
@@ -187,8 +187,7 @@ ROLLBACK;
187187
query processing.
188188
The number of blocks shown for an
189189
upper-level node includes those used by all its child nodes. In text
190-
format, only non-zero values are printed. This parameter may only be
191-
used when <literal>ANALYZE</literal> is also enabled. It defaults to
190+
format, only non-zero values are printed. It defaults to
192191
<literal>FALSE</literal>.
193192
</para>
194193
</listitem>

‎src/backend/commands/explain.c

+23-23
Original file line numberDiff line numberDiff line change
@@ -116,7 +116,8 @@ static void show_instrumentation_count(const char *qlabel, int which,
116116
static void show_foreignscan_info(ForeignScanState *fsstate, ExplainState *es);
117117
static void show_eval_params(Bitmapset *bms_params, ExplainState *es);
118118
static const char *explain_get_index_name(Oid indexId);
119-
static void show_buffer_usage(ExplainState *es, const BufferUsage *usage);
119+
static void show_buffer_usage(ExplainState *es, const BufferUsage *usage,
120+
bool planning);
120121
static void show_wal_usage(ExplainState *es, const WalUsage *usage);
121122
static void ExplainIndexScanDetails(Oid indexid, ScanDirection indexorderdir,
122123
ExplainState *es);
@@ -221,11 +222,6 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
221222
parser_errposition(pstate, opt->location)));
222223
}
223224

224-
if (es->buffers && !es->analyze)
225-
ereport(ERROR,
226-
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
227-
errmsg("EXPLAIN option BUFFERS requires ANALYZE")));
228-
229225
if (es->wal && !es->analyze)
230226
ereport(ERROR,
231227
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -586,8 +582,13 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
586582
/* Create textual dump of plan tree */
587583
ExplainPrintPlan(es, queryDesc);
588584

589-
if (es->summary && (planduration || bufusage))
585+
/* Show buffer usage in planning */
586+
if (bufusage)
587+
{
590588
ExplainOpenGroup("Planning", "Planning", true, es);
589+
show_buffer_usage(es, bufusage, true);
590+
ExplainCloseGroup("Planning", "Planning", true, es);
591+
}
591592

592593
if (es->summary && planduration)
593594
{
@@ -596,19 +597,6 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
596597
ExplainPropertyFloat("Planning Time", "ms", 1000.0 * plantime, 3, es);
597598
}
598599

599-
/* Show buffer usage */
600-
if (es->summary && bufusage)
601-
{
602-
if (es->format == EXPLAIN_FORMAT_TEXT)
603-
es->indent++;
604-
show_buffer_usage(es, bufusage);
605-
if (es->format == EXPLAIN_FORMAT_TEXT)
606-
es->indent--;
607-
}
608-
609-
if (es->summary && (planduration || bufusage))
610-
ExplainCloseGroup("Planning", "Planning", true, es);
611-
612600
/* Print info about runtime of triggers */
613601
if (es->analyze)
614602
ExplainPrintTriggers(es, queryDesc);
@@ -1996,7 +1984,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
19961984

19971985
/* Show buffer/WAL usage */
19981986
if (es->buffers && planstate->instrument)
1999-
show_buffer_usage(es, &planstate->instrument->bufusage);
1987+
show_buffer_usage(es, &planstate->instrument->bufusage, false);
20001988
if (es->wal && planstate->instrument)
20011989
show_wal_usage(es, &planstate->instrument->walusage);
20021990

@@ -2015,7 +2003,7 @@ ExplainNode(PlanState *planstate, List *ancestors,
20152003

20162004
ExplainOpenWorker(n, es);
20172005
if (es->buffers)
2018-
show_buffer_usage(es, &instrument->bufusage);
2006+
show_buffer_usage(es, &instrument->bufusage, false);
20192007
if (es->wal)
20202008
show_wal_usage(es, &instrument->walusage);
20212009
ExplainCloseWorker(n, es);
@@ -3301,7 +3289,7 @@ explain_get_index_name(Oid indexId)
33013289
* Show buffer usage details.
33023290
*/
33033291
static void
3304-
show_buffer_usage(ExplainState *es, const BufferUsage *usage)
3292+
show_buffer_usage(ExplainState *es, const BufferUsage *usage, bool planning)
33053293
{
33063294
if (es->format == EXPLAIN_FORMAT_TEXT)
33073295
{
@@ -3317,6 +3305,15 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage)
33173305
usage->temp_blks_written > 0);
33183306
bool has_timing = (!INSTR_TIME_IS_ZERO(usage->blk_read_time) ||
33193307
!INSTR_TIME_IS_ZERO(usage->blk_write_time));
3308+
bool show_planning = (planning && (has_shared ||
3309+
has_local || has_temp || has_timing));
3310+
3311+
if (show_planning)
3312+
{
3313+
ExplainIndentText(es);
3314+
appendStringInfoString(es->str, "Planning:\n");
3315+
es->indent++;
3316+
}
33203317

33213318
/* Show only positive counter values. */
33223319
if (has_shared || has_local || has_temp)
@@ -3386,6 +3383,9 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage)
33863383
INSTR_TIME_GET_MILLISEC(usage->blk_write_time));
33873384
appendStringInfoChar(es->str, '\n');
33883385
}
3386+
3387+
if (show_planning)
3388+
es->indent--;
33893389
}
33903390
else
33913391
{

‎src/test/regress/expected/explain.out

+51-4
Original file line numberDiff line numberDiff line change
@@ -106,7 +106,6 @@ select explain_filter('explain (analyze, buffers, format json) select * from int
106106
"Temp Written Blocks": N +
107107
}, +
108108
"Planning": { +
109-
"Planning Time": N.N, +
110109
"Shared Hit Blocks": N, +
111110
"Shared Read Blocks": N, +
112111
"Shared Dirtied Blocks": N, +
@@ -118,6 +117,7 @@ select explain_filter('explain (analyze, buffers, format json) select * from int
118117
"Temp Read Blocks": N, +
119118
"Temp Written Blocks": N +
120119
}, +
120+
"Planning Time": N.N, +
121121
"Triggers": [ +
122122
], +
123123
"Execution Time": N.N +
@@ -155,7 +155,6 @@ select explain_filter('explain (analyze, buffers, format xml) select * from int8
155155
<Temp-Written-Blocks>N</Temp-Written-Blocks> +
156156
</Plan> +
157157
<Planning> +
158-
<Planning-Time>N.N</Planning-Time> +
159158
<Shared-Hit-Blocks>N</Shared-Hit-Blocks> +
160159
<Shared-Read-Blocks>N</Shared-Read-Blocks> +
161160
<Shared-Dirtied-Blocks>N</Shared-Dirtied-Blocks>+
@@ -167,6 +166,7 @@ select explain_filter('explain (analyze, buffers, format xml) select * from int8
167166
<Temp-Read-Blocks>N</Temp-Read-Blocks> +
168167
<Temp-Written-Blocks>N</Temp-Written-Blocks> +
169168
</Planning> +
169+
<Planning-Time>N.N</Planning-Time> +
170170
<Triggers> +
171171
</Triggers> +
172172
<Execution-Time>N.N</Execution-Time> +
@@ -201,7 +201,6 @@ select explain_filter('explain (analyze, buffers, format yaml) select * from int
201201
Temp Read Blocks: N +
202202
Temp Written Blocks: N +
203203
Planning: +
204-
Planning Time: N.N +
205204
Shared Hit Blocks: N +
206205
Shared Read Blocks: N +
207206
Shared Dirtied Blocks: N +
@@ -212,10 +211,58 @@ select explain_filter('explain (analyze, buffers, format yaml) select * from int
212211
Local Written Blocks: N +
213212
Temp Read Blocks: N +
214213
Temp Written Blocks: N +
214+
Planning Time: N.N +
215215
Triggers: +
216216
Execution Time: N.N
217217
(1 row)
218218

219+
select explain_filter('explain (buffers, format text) select * from int8_tbl i8');
220+
explain_filter
221+
---------------------------------------------------------
222+
Seq Scan on int8_tbl i8 (cost=N.N..N.N rows=N width=N)
223+
(1 row)
224+
225+
select explain_filter('explain (buffers, format json) select * from int8_tbl i8');
226+
explain_filter
227+
------------------------------------
228+
[ +
229+
{ +
230+
"Plan": { +
231+
"Node Type": "Seq Scan", +
232+
"Parallel Aware": false, +
233+
"Relation Name": "int8_tbl",+
234+
"Alias": "i8", +
235+
"Startup Cost": N.N, +
236+
"Total Cost": N.N, +
237+
"Plan Rows": N, +
238+
"Plan Width": N, +
239+
"Shared Hit Blocks": N, +
240+
"Shared Read Blocks": N, +
241+
"Shared Dirtied Blocks": N, +
242+
"Shared Written Blocks": N, +
243+
"Local Hit Blocks": N, +
244+
"Local Read Blocks": N, +
245+
"Local Dirtied Blocks": N, +
246+
"Local Written Blocks": N, +
247+
"Temp Read Blocks": N, +
248+
"Temp Written Blocks": N +
249+
}, +
250+
"Planning": { +
251+
"Shared Hit Blocks": N, +
252+
"Shared Read Blocks": N, +
253+
"Shared Dirtied Blocks": N, +
254+
"Shared Written Blocks": N, +
255+
"Local Hit Blocks": N, +
256+
"Local Read Blocks": N, +
257+
"Local Dirtied Blocks": N, +
258+
"Local Written Blocks": N, +
259+
"Temp Read Blocks": N, +
260+
"Temp Written Blocks": N +
261+
} +
262+
} +
263+
]
264+
(1 row)
265+
219266
-- SETTINGS option
220267
-- We have to ignore other settings that might be imposed by the environment,
221268
-- so printing the whole Settings field unfortunately won't do.
@@ -402,7 +449,6 @@ select jsonb_pretty(
402449
"Shared Written Blocks": 0 +
403450
}, +
404451
"Planning": { +
405-
"Planning Time": 0.0, +
406452
"Local Hit Blocks": 0, +
407453
"Temp Read Blocks": 0, +
408454
"Local Read Blocks": 0, +
@@ -416,6 +462,7 @@ select jsonb_pretty(
416462
}, +
417463
"Triggers": [ +
418464
], +
465+
"Planning Time": 0.0, +
419466
"Execution Time": 0.0 +
420467
} +
421468
]

‎src/test/regress/sql/explain.sql

+2
Original file line numberDiff line numberDiff line change
@@ -57,6 +57,8 @@ select explain_filter('explain (analyze, buffers, format text) select * from int
5757
select explain_filter('explain (analyze, buffers, format json) select * from int8_tbl i8');
5858
select explain_filter('explain (analyze, buffers, format xml) select * from int8_tbl i8');
5959
select explain_filter('explain (analyze, buffers, format yaml) select * from int8_tbl i8');
60+
select explain_filter('explain (buffers, format text) select * from int8_tbl i8');
61+
select explain_filter('explain (buffers, format json) select * from int8_tbl i8');
6062

6163
-- SETTINGS option
6264
-- We have to ignore other settings that might be imposed by the environment,

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