[CF 5359] Showing applied extended statistics in explain Part2

This branch was automatically generated by a robot using patches from an
email thread registered at:

https://commitfest.postgresql.org/patch/5359

The branch will be overwritten each time a new patch version is posted to
the thread, and also periodically to check for bitrot caused by changes
on the master branch.

Patch(es): https://www.postgresql.org/message-id/CAOKkKFtaCPamg-GRtUjADGbzXCL0exhkK5FiznkJB-8-dANf1Q@mail.gmail.com
Author(s): Tatsuro Yamada

Author: Commitfest Bot

contrib/auto_explain/auto_explain.c

@@ -30,6 +30,7 @@ static bool auto_explain_log_analyze = false;
 static bool auto_explain_log_verbose = false;
 static bool auto_explain_log_buffers = false;
 static bool auto_explain_log_wal = false;
+static bool auto_explain_log_stats = false;
 static bool auto_explain_log_triggers = false;
 static bool auto_explain_log_timing = true;
 static bool auto_explain_log_settings = false;
@@ -171,6 +172,17 @@ _PG_init(void)
 							 NULL,
 							 NULL);
 
+	DefineCustomBoolVariable("auto_explain.log_stats",
+							 "Use EXPLAIN STATS for plan logging.",
+							 NULL,
+							 &auto_explain_log_stats,
+							 false,
+							 PGC_SUSET,
+							 0,
+							 NULL,
+							 NULL,
+							 NULL);
+
 	DefineCustomBoolVariable("auto_explain.log_triggers",
 							 "Include trigger statistics in plans.",
 							 "This has no effect unless log_analyze is also set.",
@@ -405,6 +417,7 @@ explain_ExecutorEnd(QueryDesc *queryDesc)
 			es->summary = es->analyze;
 			/* No support for MEMORY */
 			/* es->memory = false; */
+			es->stats = auto_explain_log_stats;
 			es->format = auto_explain_log_format;
 			es->settings = auto_explain_log_settings;
 

doc/src/sgml/auto-explain.sgml

@@ -148,6 +148,24 @@ LOAD 'auto_explain';
     </listitem>
    </varlistentry>
 
+   <varlistentry id="auto-explain-configuration-parameters-log-stats">
+    <term>
+     <varname>auto_explain.log_stats</varname> (<type>boolean</type>)
+     <indexterm>
+      <primary><varname>auto_explain.log_stats</varname> configuration parameter</primary>
+     </indexterm>
+    </term>
+    <listitem>
+     <para>
+      <varname>auto_explain.log_stats</varname> controls whether applied
+      Extended Statistic are printed when an execution plan is logged; it's
+      equivalent to the <literal>STATS</literal> option of <command>EXPLAIN</command>.
+      This parameter is off by default.
+      Only superusers can change this setting.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry id="auto-explain-configuration-parameters-log-timing">
     <term>
      <varname>auto_explain.log_timing</varname> (<type>boolean</type>)

doc/src/sgml/ref/explain.sgml

@@ -43,6 +43,7 @@ EXPLAIN [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] <rep
     BUFFERS [ <replaceable class="parameter">boolean</replaceable> ]
     SERIALIZE [ { NONE | TEXT | BINARY } ]
     WAL [ <replaceable class="parameter">boolean</replaceable> ]
+    STATS [ <replaceable class="parameter">boolean</replaceable> ]
     TIMING [ <replaceable class="parameter">boolean</replaceable> ]
     SUMMARY [ <replaceable class="parameter">boolean</replaceable> ]
     MEMORY [ <replaceable class="parameter">boolean</replaceable> ]
@@ -251,6 +252,19 @@ ROLLBACK;
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><literal>STATS</literal></term>
+    <listitem>
+     <para>
+      Include information on applied <literal>Extended statistics</literal>.
+      Specifically, include the names of extended statistics and clauses.
+      Supported extended statistics types are Dependencies and MCV.
+      See <xref linkend="planner-stats-extended"/> for details about extended
+      statistics. This parameter defaults to <literal>FALSE</literal>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><literal>TIMING</literal></term>
     <listitem>

src/backend/commands/explain.c

@@ -82,6 +82,15 @@ static void show_qual(List *qual, const char *qlabel,
 static void show_scan_qual(List *qual, const char *qlabel,
 						   PlanState *planstate, List *ancestors,
 						   ExplainState *es);
+static char *deparse_stat_expression(Node *node,
+									 PlanState *planstate, List *ancestors,
+									 bool useprefix, ExplainState *es);
+static char *show_stat_qual(List *qual, int is_or,
+							PlanState *planstate, List *ancestors,
+							bool useprefix, ExplainState *es);
+static void show_scan_stats(List *stats, List *clauses, List *ors,
+							PlanState *planstate, List *ancestors,
+							ExplainState *es);
 static void show_upper_qual(List *qual, const char *qlabel,
 							PlanState *planstate, List *ancestors,
 							ExplainState *es);
@@ -197,6 +206,8 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 			es->settings = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "generic_plan") == 0)
 			es->generic = defGetBoolean(opt);
+		else if (strcmp(opt->defname, "stats") == 0)
+			es->stats = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "timing") == 0)
 		{
 			timing_set = true;
@@ -471,6 +482,11 @@ standard_ExplainOneQuery(Query *query, int cursorOptions,
 
 	if (es->buffers)
 		bufusage_start = pgBufferUsage;
+
+	/* if this flag is true, applied ext stats are stored */
+	if (es->stats)
+		query->isExplain_Stats = true;
+
 	INSTR_TIME_SET_CURRENT(planstart);
 
 	/* plan the query */
@@ -2096,6 +2112,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_IndexOnlyScan:
 			show_scan_qual(((IndexOnlyScan *) plan)->indexqual,
@@ -2112,10 +2133,20 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (es->analyze)
 				ExplainPropertyFloat("Heap Fetches", NULL,
 									 planstate->instrument->ntuples2, 0, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_BitmapIndexScan:
 			show_scan_qual(((BitmapIndexScan *) plan)->indexqualorig,
 						   "Index Cond", planstate, ancestors, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_BitmapHeapScan:
 			show_scan_qual(((BitmapHeapScan *) plan)->bitmapqualorig,
@@ -2146,6 +2177,12 @@ ExplainNode(PlanState *planstate, List *ancestors,
 										   planstate, es);
 			if (IsA(plan, CteScan))
 				show_ctescan_info(castNode(CteScanState, planstate), es);
+
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_Gather:
 			{
@@ -2213,6 +2250,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_TableFuncScan:
 			if (es->verbose)
@@ -2327,6 +2369,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_WindowAgg:
 			show_upper_qual(plan->qual, "Filter", planstate, ancestors, es);
@@ -2343,6 +2390,11 @@ ExplainNode(PlanState *planstate, List *ancestors,
 			if (plan->qual)
 				show_instrumentation_count("Rows Removed by Filter", 1,
 										   planstate, es);
+			if (es->stats)
+				show_scan_stats(plan->app_extstats->applied_stats,
+								plan->app_extstats->applied_clauses,
+								plan->app_extstats->applied_clauses_or,
+								planstate, ancestors, es);
 			break;
 		case T_Sort:
 			show_sort_keys(castNode(SortState, planstate), ancestors, es);
@@ -2669,6 +2721,94 @@ show_scan_qual(List *qual, const char *qlabel,
 	show_qual(qual, qlabel, planstate, ancestors, useprefix, es);
 }
 
+/*
+ * Show a generic expression
+ */
+static char *
+deparse_stat_expression(Node *node,
+						PlanState *planstate, List *ancestors,
+						bool useprefix, ExplainState *es)
+{
+	List	   *context;
+
+	/* Set up deparsing context */
+	context = set_deparse_context_plan(es->deparse_cxt,
+									   planstate->plan,
+									   ancestors);
+
+	/* Deparse the expression */
+	return deparse_expression(node, context, useprefix, false);
+}
+
+/*
+ * Show a qualifier expression for extended stats
+ */
+static char *
+show_stat_qual(List *qual, int is_or,
+			   PlanState *planstate, List *ancestors,
+			   bool useprefix, ExplainState *es)
+{
+	Node	   *node;
+
+	/* No work if empty qual */
+	if (qual == NIL)
+		return NULL;
+
+	/* Convert AND list to explicit AND */
+	switch (is_or)
+	{
+		case 0:
+			node = (Node *) make_ands_explicit(qual);
+			break;
+		case 1:
+			node = (Node *) make_ors_explicit(qual);
+			break;
+		case 2:
+			/* Extended stats for GROUP BY clause should be comma separeted string */
+			node = (Node *) qual;
+			break;
+		default:
+			elog(ERROR, "unexpected value: %d", is_or);
+			break;
+	}
+
+	/* And show it */
+	return deparse_stat_expression(node, planstate, ancestors, useprefix, es);
+}
+
+/*
+ * Show applied statistics for scan/agg/group plan node
+ */
+static void
+show_scan_stats(List *stats, List *clauses, List *ors,
+				PlanState *planstate, List *ancestors, ExplainState *es)
+{
+	ListCell   *lc1, *lc2, *lc3;
+	StringInfoData	str;
+	bool		useprefix;
+
+	useprefix = es->verbose;
+
+	forthree (lc1, stats, lc2, clauses, lc3, ors)
+	{
+		StatisticExtInfo   *stat = (StatisticExtInfo *) lfirst(lc1);
+		List   *applied_clauses = (List *) lfirst(lc2);
+		int		is_or = lfirst_int(lc3);
+
+		initStringInfo(&str);
+
+		if (useprefix)
+			appendStringInfo(&str, "%s.",
+							 get_namespace_name(get_statistics_namespace(stat->statOid)));
+
+		appendStringInfo(&str, "%s  Clauses: %s",
+						 get_statistics_name(stat->statOid),
+						 show_stat_qual(applied_clauses, is_or, planstate, ancestors, useprefix, es));
+
+		ExplainPropertyText("Ext Stats", str.data, es);
+	}
+}
+
 /*
  * Show a qualifier expression for an upper-level plan node
  */

src/backend/nodes/makefuncs.c

@@ -759,6 +759,17 @@ make_ands_explicit(List *andclauses)
 		return make_andclause(andclauses);
 }
 
+Expr *
+make_ors_explicit(List *orclauses)
+{
+	if (orclauses == NIL)
+		return (Expr *) makeBoolConst(true, false);
+	else if (list_length(orclauses) == 1)
+		return (Expr *) linitial(orclauses);
+	else
+		return make_orclause(orclauses);
+}
+
 List *
 make_ands_implicit(Expr *clause)
 {

src/backend/optimizer/plan/createplan.c

@@ -5455,13 +5455,30 @@ order_qual_clauses(PlannerInfo *root, List *clauses)
 static void
 copy_generic_path_info(Plan *dest, Path *src)
 {
+	ListCell *lc;
+
 	dest->disabled_nodes = src->disabled_nodes;
 	dest->startup_cost = src->startup_cost;
 	dest->total_cost = src->total_cost;
 	dest->plan_rows = src->rows;
 	dest->plan_width = src->pathtarget->width;
 	dest->parallel_aware = src->parallel_aware;
 	dest->parallel_safe = src->parallel_safe;
+
+	/* Is this the right place to use makeNode()? */
+	dest->app_extstats = makeNode(Applied_ExtStats);
+	dest->app_extstats->applied_stats = src->parent->applied_stats;
+	dest->app_extstats->applied_clauses_or = src->parent->applied_clauses_or;
+	dest->app_extstats->applied_clauses = NIL;
+
+	foreach (lc, src->parent->applied_clauses)
+	{
+		List *clauses = (List *) lfirst(lc);
+
+		dest->app_extstats->applied_clauses
+			= lappend(dest->app_extstats->applied_clauses,
+					  maybe_extract_actual_clauses(clauses, false));
+	}
 }
 
 /*

src/backend/optimizer/util/relnode.c

@@ -287,6 +287,10 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptInfo *parent)
 	rel->partexprs = NULL;
 	rel->nullable_partexprs = NULL;
 
+	rel->applied_stats = NIL;
+	rel->applied_clauses = NIL;
+	rel->applied_clauses_or = NIL;
+
 	/*
 	 * Pass assorted information down the inheritance hierarchy.
 	 */
@@ -769,6 +773,10 @@ build_join_rel(PlannerInfo *root,
 	joinrel->partexprs = NULL;
 	joinrel->nullable_partexprs = NULL;
 
+	joinrel->applied_stats = NIL;
+	joinrel->applied_clauses = NIL;
+	joinrel->applied_clauses_or = NIL;
+
 	/* Compute information relevant to the foreign relations. */
 	set_foreign_rel_properties(joinrel, outer_rel, inner_rel);
 
@@ -953,6 +961,10 @@ build_child_join_rel(PlannerInfo *root, RelOptInfo *outer_rel,
 	joinrel->partexprs = NULL;
 	joinrel->nullable_partexprs = NULL;
 
+	joinrel->applied_stats = NIL;
+	joinrel->applied_clauses = NIL;
+	joinrel->applied_clauses_or = NIL;
+
 	/* Compute information relevant to foreign relations. */
 	set_foreign_rel_properties(joinrel, outer_rel, inner_rel);