Extend EXPLAIN to allow generic options to be specified.

The original syntax made it difficult to add options without making them
into reserved words.  This change parenthesizes the options to avoid that
problem, and makes provision for an explicit (and perhaps non-Boolean)
value for each option.  The original syntax is still supported, but only
for the two original options ANALYZE and VERBOSE.

As a test case, add a COSTS option that can suppress the planner cost
estimates.  This may be useful for including EXPLAIN output in the regression
tests, which are otherwise unable to cope with cross-platform variations in
cost estimates.

Robert Haas

1 files changed, 91 insertions, 80 deletions

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 899f2581bc4..1388c8dd42f 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994-5, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.187 2009/07/24 21:08:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.188 2009/07/26 23:34:17 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,6 +16,7 @@
 #include "access/xact.h"
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_type.h"
+#include "commands/defrem.h"
 #include "commands/explain.h"
 #include "commands/prepare.h"
 #include "commands/trigger.h"
@@ -40,20 +41,8 @@ ExplainOneQuery_hook_type ExplainOneQuery_hook = NULL;
 explain_get_index_name_hook_type explain_get_index_name_hook = NULL;
 
 
-typedef struct ExplainState
-{
-	StringInfo	str;			/* output buffer */
-	/* options */
-	bool		printTList;		/* print plan targetlists */
-	bool		printAnalyze;	/* print actual times */
-	/* other states */
-	PlannedStmt *pstmt;			/* top of plan */
-	List	   *rtable;			/* range table */
-} ExplainState;
-
-static void ExplainOneQuery(Query *query, ExplainStmt *stmt,
-				const char *queryString,
-				ParamListInfo params, TupOutputState *tstate);
+static void ExplainOneQuery(Query *query, ExplainState *es,
+				const char *queryString, ParamListInfo params);
 static void report_triggers(ResultRelInfo *rInfo, bool show_relname,
 				StringInfo buf);
 static double elapsed_time(instr_time *starttime);
@@ -84,11 +73,33 @@ void
 ExplainQuery(ExplainStmt *stmt, const char *queryString,
 			 ParamListInfo params, DestReceiver *dest)
 {
+	ExplainState es;
 	Oid		   *param_types;
 	int			num_params;
 	TupOutputState *tstate;
 	List	   *rewritten;
-	ListCell   *l;
+	ListCell   *lc;
+
+	/* Initialize ExplainState. */
+	ExplainInitState(&es);
+
+	/* Parse options list. */
+	foreach(lc, stmt->options)
+	{
+		DefElem *opt = (DefElem *) lfirst(lc);
+
+		if (strcmp(opt->defname, "analyze") == 0)
+			es.analyze = defGetBoolean(opt);
+		else if (strcmp(opt->defname, "verbose") == 0)
+			es.verbose = defGetBoolean(opt);
+		else if (strcmp(opt->defname, "costs") == 0)
+			es.costs = defGetBoolean(opt);
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("unrecognized EXPLAIN option \"%s\"",
+							opt->defname)));
+	}
 
 	/* Convert parameter type data to the form parser wants */
 	getParamListTypes(params, &param_types, &num_params);
@@ -106,28 +117,44 @@ ExplainQuery(ExplainStmt *stmt, const char *queryString,
 	rewritten = pg_analyze_and_rewrite((Node *) copyObject(stmt->query),
 									   queryString, param_types, num_params);
 
-	/* prepare for projection of tuples */
-	tstate = begin_tup_output_tupdesc(dest, ExplainResultDesc(stmt));
-
 	if (rewritten == NIL)
 	{
 		/* In the case of an INSTEAD NOTHING, tell at least that */
-		do_text_output_oneline(tstate, "Query rewrites to nothing");
+		appendStringInfoString(es.str, "Query rewrites to nothing\n");
 	}
 	else
 	{
+		ListCell   *l;
+
 		/* Explain every plan */
 		foreach(l, rewritten)
 		{
-			ExplainOneQuery((Query *) lfirst(l), stmt,
-							queryString, params, tstate);
+			ExplainOneQuery((Query *) lfirst(l), &es, queryString, params);
 			/* put a blank line between plans */
 			if (lnext(l) != NULL)
-				do_text_output_oneline(tstate, "");
+				appendStringInfoChar(es.str, '\n');
 		}
 	}
 
+	/* output tuples */
+	tstate = begin_tup_output_tupdesc(dest, ExplainResultDesc(stmt));
+	do_text_output_multiline(tstate, es.str->data);
 	end_tup_output(tstate);
+
+	pfree(es.str->data);
+}
+
+/*
+ * Initialize ExplainState.
+ */
+void
+ExplainInitState(ExplainState *es)
+{
+	/* Set default options. */
+	memset(es, 0, sizeof(ExplainState));
+	es->costs = true;
+	/* Prepare output buffer. */
+	es->str = makeStringInfo();
 }
 
 /*
@@ -151,20 +178,19 @@ ExplainResultDesc(ExplainStmt *stmt)
  *	  print out the execution plan for one Query
  */
 static void
-ExplainOneQuery(Query *query, ExplainStmt *stmt, const char *queryString,
-				ParamListInfo params, TupOutputState *tstate)
+ExplainOneQuery(Query *query, ExplainState *es,
+				const char *queryString, ParamListInfo params)
 {
 	/* planner will not cope with utility statements */
 	if (query->commandType == CMD_UTILITY)
 	{
-		ExplainOneUtility(query->utilityStmt, stmt,
-						  queryString, params, tstate);
+		ExplainOneUtility(query->utilityStmt, es, queryString, params);
 		return;
 	}
 
 	/* if an advisor plugin is present, let it manage things */
 	if (ExplainOneQuery_hook)
-		(*ExplainOneQuery_hook) (query, stmt, queryString, params, tstate);
+		(*ExplainOneQuery_hook) (query, es, queryString, params);
 	else
 	{
 		PlannedStmt *plan;
@@ -173,7 +199,7 @@ ExplainOneQuery(Query *query, ExplainStmt *stmt, const char *queryString,
 		plan = pg_plan_query(query, 0, params);
 
 		/* run it (if needed) and produce output */
-		ExplainOnePlan(plan, stmt, queryString, params, tstate);
+		ExplainOnePlan(plan, es, queryString, params);
 	}
 }
 
@@ -187,21 +213,20 @@ ExplainOneQuery(Query *query, ExplainStmt *stmt, const char *queryString,
  * EXPLAIN EXECUTE case
  */
 void
-ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
-				  const char *queryString, ParamListInfo params,
-				  TupOutputState *tstate)
+ExplainOneUtility(Node *utilityStmt, ExplainState *es,
+				  const char *queryString, ParamListInfo params)
 {
 	if (utilityStmt == NULL)
 		return;
 
 	if (IsA(utilityStmt, ExecuteStmt))
-		ExplainExecuteQuery((ExecuteStmt *) utilityStmt, stmt,
-							queryString, params, tstate);
+		ExplainExecuteQuery((ExecuteStmt *) utilityStmt, es,
+							queryString, params);
 	else if (IsA(utilityStmt, NotifyStmt))
-		do_text_output_oneline(tstate, "NOTIFY");
+		appendStringInfoString(es->str, "NOTIFY\n");
 	else
-		do_text_output_oneline(tstate,
-							   "Utility statements have no plan structure");
+		appendStringInfoString(es->str,
+							   "Utility statements have no plan structure\n");
 }
 
 /*
@@ -219,14 +244,12 @@ ExplainOneUtility(Node *utilityStmt, ExplainStmt *stmt,
  * to call it.
  */
 void
-ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
-			   const char *queryString, ParamListInfo params,
-			   TupOutputState *tstate)
+ExplainOnePlan(PlannedStmt *plannedstmt, ExplainState *es,
+			   const char *queryString, ParamListInfo params)
 {
 	QueryDesc  *queryDesc;
 	instr_time	starttime;
 	double		totaltime = 0;
-	StringInfoData buf;
 	int			eflags;
 
 	/*
@@ -238,17 +261,16 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
 	/* Create a QueryDesc requesting no output */
 	queryDesc = CreateQueryDesc(plannedstmt, queryString,
 								GetActiveSnapshot(), InvalidSnapshot,
-								None_Receiver, params,
-								stmt->analyze);
+								None_Receiver, params, es->analyze);
 
 	INSTR_TIME_SET_CURRENT(starttime);
 
 	/* If analyzing, we need to cope with queued triggers */
-	if (stmt->analyze)
+	if (es->analyze)
 		AfterTriggerBeginQuery();
 
 	/* Select execution options */
-	if (stmt->analyze)
+	if (es->analyze)
 		eflags = 0;				/* default run-to-completion flags */
 	else
 		eflags = EXEC_FLAG_EXPLAIN_ONLY;
@@ -257,7 +279,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
 	ExecutorStart(queryDesc, eflags);
 
 	/* Execute the plan for statistics if asked for */
-	if (stmt->analyze)
+	if (es->analyze)
 	{
 		/* run the plan */
 		ExecutorRun(queryDesc, ForwardScanDirection, 0L);
@@ -267,15 +289,14 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
 	}
 
 	/* Create textual dump of plan tree */
-	initStringInfo(&buf);
-	ExplainPrintPlan(&buf, queryDesc, stmt->analyze, stmt->verbose);
+	ExplainPrintPlan(es, queryDesc);
 
 	/*
 	 * If we ran the command, run any AFTER triggers it queued.  (Note this
 	 * will not include DEFERRED triggers; since those don't run until end of
 	 * transaction, we can't measure them.)  Include into total runtime.
 	 */
-	if (stmt->analyze)
+	if (es->analyze)
 	{
 		INSTR_TIME_SET_CURRENT(starttime);
 		AfterTriggerEndQuery(queryDesc->estate);
@@ -283,7 +304,7 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
 	}
 
 	/* Print info about runtime of triggers */
-	if (stmt->analyze)
+	if (es->analyze)
 	{
 		ResultRelInfo *rInfo;
 		bool		show_relname;
@@ -295,12 +316,12 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
 		show_relname = (numrels > 1 || targrels != NIL);
 		rInfo = queryDesc->estate->es_result_relations;
 		for (nr = 0; nr < numrels; rInfo++, nr++)
-			report_triggers(rInfo, show_relname, &buf);
+			report_triggers(rInfo, show_relname, es->str);
 
 		foreach(l, targrels)
 		{
 			rInfo = (ResultRelInfo *) lfirst(l);
-			report_triggers(rInfo, show_relname, &buf);
+			report_triggers(rInfo, show_relname, es->str);
 		}
 	}
 
@@ -317,45 +338,34 @@ ExplainOnePlan(PlannedStmt *plannedstmt, ExplainStmt *stmt,
 	PopActiveSnapshot();
 
 	/* We need a CCI just in case query expanded to multiple plans */
-	if (stmt->analyze)
+	if (es->analyze)
 		CommandCounterIncrement();
 
 	totaltime += elapsed_time(&starttime);
 
-	if (stmt->analyze)
-		appendStringInfo(&buf, "Total runtime: %.3f ms\n",
+	if (es->analyze)
+		appendStringInfo(es->str, "Total runtime: %.3f ms\n",
 						 1000.0 * totaltime);
-	do_text_output_multiline(tstate, buf.data);
-
-	pfree(buf.data);
 }
 
 /*
  * ExplainPrintPlan -
- *	  convert a QueryDesc's plan tree to text and append it to 'str'
+ *	  convert a QueryDesc's plan tree to text and append it to es->str
  *
- * 'analyze' means to include runtime instrumentation results
- * 'verbose' means a verbose printout (currently, it shows targetlists)
+ * The caller should have set up the options fields of *es, as well as
+ * initializing the output buffer es->str.  Other fields in *es are
+ * initialized here.
  *
  * NB: will not work on utility statements
  */
 void
-ExplainPrintPlan(StringInfo str, QueryDesc *queryDesc,
-				 bool analyze, bool verbose)
+ExplainPrintPlan(ExplainState *es, QueryDesc *queryDesc)
 {
-	ExplainState es;
-
 	Assert(queryDesc->plannedstmt != NULL);
-
-	memset(&es, 0, sizeof(es));
-	es.str = str;
-	es.printTList = verbose;
-	es.printAnalyze = analyze;
-	es.pstmt = queryDesc->plannedstmt;
-	es.rtable = queryDesc->plannedstmt->rtable;
-
+	es->pstmt = queryDesc->plannedstmt;
+	es->rtable = queryDesc->plannedstmt->rtable;
 	ExplainNode(queryDesc->plannedstmt->planTree, queryDesc->planstate,
-				NULL, 0, &es);
+				NULL, 0, es);
 }
 
 /*
@@ -692,9 +702,10 @@ ExplainNode(Plan *plan, PlanState *planstate,
 			break;
 	}
 
-	appendStringInfo(es->str, "  (cost=%.2f..%.2f rows=%.0f width=%d)",
-					 plan->startup_cost, plan->total_cost,
-					 plan->plan_rows, plan->plan_width);
+	if (es->costs)
+		appendStringInfo(es->str, "  (cost=%.2f..%.2f rows=%.0f width=%d)",
+						 plan->startup_cost, plan->total_cost,
+						 plan->plan_rows, plan->plan_width);
 
 	/*
 	 * We have to forcibly clean up the instrumentation state because we
@@ -714,12 +725,12 @@ ExplainNode(Plan *plan, PlanState *planstate,
 						 planstate->instrument->ntuples / nloops,
 						 planstate->instrument->nloops);
 	}
-	else if (es->printAnalyze)
+	else if (es->analyze)
 		appendStringInfoString(es->str, " (never executed)");
 	appendStringInfoChar(es->str, '\n');
 
 	/* target list */
-	if (es->printTList)
+	if (es->verbose)
 		show_plan_tlist(plan, indent, es);
 
 	/* quals, sort keys, etc */
@@ -1025,7 +1036,7 @@ static void
 show_sort_info(SortState *sortstate, int indent, ExplainState *es)
 {
 	Assert(IsA(sortstate, SortState));
-	if (es->printAnalyze && sortstate->sort_Done &&
+	if (es->analyze && sortstate->sort_Done &&
 		sortstate->tuplesortstate != NULL)
 	{
 		char	   *sortinfo;