From 9d701e624f4b9386cbd99519dab7936afe3d5aed Mon Sep 17 00:00:00 2001 From: Fujii Masao Date: Fri, 21 Aug 2020 20:48:59 +0900 Subject: [PATCH] Rework EXPLAIN for planner's buffer usage. Commit ce77abe63c 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 --- doc/src/sgml/ref/explain.sgml | 3 +- src/backend/commands/explain.c | 46 +++++++++++----------- src/test/regress/expected/explain.out | 55 +++++++++++++++++++++++++-- src/test/regress/sql/explain.sql | 2 + 4 files changed, 77 insertions(+), 29 deletions(-) diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml index 1c19e254dc240..906b2ccd50a2f 100644 --- a/doc/src/sgml/ref/explain.sgml +++ b/doc/src/sgml/ref/explain.sgml @@ -187,8 +187,7 @@ ROLLBACK; query processing. The number of blocks shown for an upper-level node includes those used by all its child nodes. In text - format, only non-zero values are printed. This parameter may only be - used when ANALYZE is also enabled. It defaults to + format, only non-zero values are printed. It defaults to FALSE. diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 30e0a7ee7f219..c98c9b5547c5a 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -116,7 +116,8 @@ static void show_instrumentation_count(const char *qlabel, int which, 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_buffer_usage(ExplainState *es, const BufferUsage *usage, + bool planning); static void show_wal_usage(ExplainState *es, const WalUsage *usage); static void ExplainIndexScanDetails(Oid indexid, ScanDirection indexorderdir, ExplainState *es); @@ -221,11 +222,6 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt, parser_errposition(pstate, opt->location))); } - if (es->buffers && !es->analyze) - ereport(ERROR, - (errcode(ERRCODE_INVALID_PARAMETER_VALUE), - errmsg("EXPLAIN option BUFFERS requires ANALYZE"))); - if (es->wal && !es->analyze) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), @@ -586,8 +582,13 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es, /* Create textual dump of plan tree */ ExplainPrintPlan(es, queryDesc); - if (es->summary && (planduration || bufusage)) + /* Show buffer usage in planning */ + if (bufusage) + { ExplainOpenGroup("Planning", "Planning", true, es); + show_buffer_usage(es, bufusage, true); + ExplainCloseGroup("Planning", "Planning", true, es); + } if (es->summary && planduration) { @@ -596,19 +597,6 @@ 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); @@ -1996,7 +1984,7 @@ ExplainNode(PlanState *planstate, List *ancestors, /* Show buffer/WAL usage */ if (es->buffers && planstate->instrument) - show_buffer_usage(es, &planstate->instrument->bufusage); + show_buffer_usage(es, &planstate->instrument->bufusage, false); if (es->wal && planstate->instrument) show_wal_usage(es, &planstate->instrument->walusage); @@ -2015,7 +2003,7 @@ ExplainNode(PlanState *planstate, List *ancestors, ExplainOpenWorker(n, es); if (es->buffers) - show_buffer_usage(es, &instrument->bufusage); + show_buffer_usage(es, &instrument->bufusage, false); if (es->wal) show_wal_usage(es, &instrument->walusage); ExplainCloseWorker(n, es); @@ -3301,7 +3289,7 @@ explain_get_index_name(Oid indexId) * Show buffer usage details. */ static void -show_buffer_usage(ExplainState *es, const BufferUsage *usage) +show_buffer_usage(ExplainState *es, const BufferUsage *usage, bool planning) { if (es->format == EXPLAIN_FORMAT_TEXT) { @@ -3317,6 +3305,15 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage) usage->temp_blks_written > 0); bool has_timing = (!INSTR_TIME_IS_ZERO(usage->blk_read_time) || !INSTR_TIME_IS_ZERO(usage->blk_write_time)); + bool show_planning = (planning && (has_shared || + has_local || has_temp || has_timing)); + + if (show_planning) + { + ExplainIndentText(es); + appendStringInfoString(es->str, "Planning:\n"); + es->indent++; + } /* Show only positive counter values. */ if (has_shared || has_local || has_temp) @@ -3386,6 +3383,9 @@ show_buffer_usage(ExplainState *es, const BufferUsage *usage) INSTR_TIME_GET_MILLISEC(usage->blk_write_time)); appendStringInfoChar(es->str, '\n'); } + + if (show_planning) + es->indent--; } else { diff --git a/src/test/regress/expected/explain.out b/src/test/regress/expected/explain.out index 96baba038c2e2..a1ee6c6792560 100644 --- a/src/test/regress/expected/explain.out +++ b/src/test/regress/expected/explain.out @@ -106,7 +106,6 @@ select explain_filter('explain (analyze, buffers, format json) select * from int "Temp Written Blocks": N + }, + "Planning": { + - "Planning Time": N.N, + "Shared Hit Blocks": N, + "Shared Read Blocks": N, + "Shared Dirtied Blocks": N, + @@ -118,6 +117,7 @@ select explain_filter('explain (analyze, buffers, format json) select * from int "Temp Read Blocks": N, + "Temp Written Blocks": N + }, + + "Planning Time": N.N, + "Triggers": [ + ], + "Execution Time": N.N + @@ -155,7 +155,6 @@ select explain_filter('explain (analyze, buffers, format xml) select * from int8 N + + + - N.N + N + N + N+ @@ -167,6 +166,7 @@ select explain_filter('explain (analyze, buffers, format xml) select * from int8 N + N + + + N.N + + + N.N + @@ -201,7 +201,6 @@ select explain_filter('explain (analyze, buffers, format yaml) select * from int Temp Read Blocks: N + Temp Written Blocks: N + Planning: + - Planning Time: N.N + Shared Hit Blocks: N + Shared Read Blocks: N + Shared Dirtied Blocks: N + @@ -212,10 +211,58 @@ select explain_filter('explain (analyze, buffers, format yaml) select * from int Local Written Blocks: N + Temp Read Blocks: N + Temp Written Blocks: N + + Planning Time: N.N + Triggers: + Execution Time: N.N (1 row) +select explain_filter('explain (buffers, format text) select * from int8_tbl i8'); + explain_filter +--------------------------------------------------------- + Seq Scan on int8_tbl i8 (cost=N.N..N.N rows=N width=N) +(1 row) + +select explain_filter('explain (buffers, format json) select * from int8_tbl i8'); + explain_filter +------------------------------------ + [ + + { + + "Plan": { + + "Node Type": "Seq Scan", + + "Parallel Aware": false, + + "Relation Name": "int8_tbl",+ + "Alias": "i8", + + "Startup Cost": N.N, + + "Total Cost": N.N, + + "Plan Rows": N, + + "Plan Width": N, + + "Shared Hit Blocks": N, + + "Shared Read Blocks": N, + + "Shared Dirtied Blocks": N, + + "Shared Written Blocks": N, + + "Local Hit Blocks": N, + + "Local Read Blocks": N, + + "Local Dirtied Blocks": N, + + "Local Written Blocks": N, + + "Temp Read Blocks": N, + + "Temp Written Blocks": N + + }, + + "Planning": { + + "Shared Hit Blocks": N, + + "Shared Read Blocks": N, + + "Shared Dirtied Blocks": N, + + "Shared Written Blocks": N, + + "Local Hit Blocks": N, + + "Local Read Blocks": N, + + "Local Dirtied Blocks": N, + + "Local Written Blocks": N, + + "Temp Read Blocks": N, + + "Temp Written Blocks": N + + } + + } + + ] +(1 row) + -- SETTINGS option -- We have to ignore other settings that might be imposed by the environment, -- so printing the whole Settings field unfortunately won't do. @@ -402,7 +449,6 @@ select jsonb_pretty( "Shared Written Blocks": 0 + }, + "Planning": { + - "Planning Time": 0.0, + "Local Hit Blocks": 0, + "Temp Read Blocks": 0, + "Local Read Blocks": 0, + @@ -416,6 +462,7 @@ select jsonb_pretty( }, + "Triggers": [ + ], + + "Planning Time": 0.0, + "Execution Time": 0.0 + } + ] diff --git a/src/test/regress/sql/explain.sql b/src/test/regress/sql/explain.sql index dce2a34207246..01783c607aa06 100644 --- a/src/test/regress/sql/explain.sql +++ b/src/test/regress/sql/explain.sql @@ -57,6 +57,8 @@ select explain_filter('explain (analyze, buffers, format text) select * from int select explain_filter('explain (analyze, buffers, format json) select * from int8_tbl i8'); select explain_filter('explain (analyze, buffers, format xml) select * from int8_tbl i8'); select explain_filter('explain (analyze, buffers, format yaml) select * from int8_tbl i8'); +select explain_filter('explain (buffers, format text) select * from int8_tbl i8'); +select explain_filter('explain (buffers, format json) select * from int8_tbl i8'); -- SETTINGS option -- We have to ignore other settings that might be imposed by the environment,