0002-Expose-counters-of-plancache-to-pg_prepared_statement.patch

diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c
index 80d6df8..36ff2f9 100644
--- a/src/backend/commands/prepare.c
+++ b/src/backend/commands/prepare.c
@@ -723,7 +723,7 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
 	 * build tupdesc for result tuples. This must match the definition of the
 	 * pg_prepared_statements view in system_views.sql
 	 */
-	tupdesc = CreateTemplateTupleDesc(5);
+	tupdesc = CreateTemplateTupleDesc(11);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "name",
 					   TEXTOID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 2, "statement",
@@ -734,6 +734,18 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
 					   REGTYPEARRAYOID, -1, 0);
 	TupleDescInitEntry(tupdesc, (AttrNumber) 5, "from_sql",
 					   BOOLOID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 6, "calls",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 7, "custom_calls",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 8, "plan_generation",
+					   INT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 9, "generic_cost",
+					   FLOAT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 10, "custom_cost",
+					   FLOAT8OID, -1, 0);
+	TupleDescInitEntry(tupdesc, (AttrNumber) 11, "last_plan",
+					   TEXTOID, -1, 0);
 
 	/*
 	 * We put all the tuples into a tuplestore in one scan of the hashtable.
@@ -755,8 +767,8 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
 		hash_seq_init(&hash_seq, prepared_queries);
 		while ((prep_stmt = hash_seq_search(&hash_seq)) != NULL)
 		{
-			Datum		values[5];
-			bool		nulls[5];
+			Datum		values[11];
+			bool		nulls[11];
 
 			MemSet(nulls, 0, sizeof(nulls));
 
@@ -766,6 +778,27 @@ pg_prepared_statement(PG_FUNCTION_ARGS)
 			values[3] = build_regtype_array(prep_stmt->plansource->param_types,
 											prep_stmt->plansource->num_params);
 			values[4] = BoolGetDatum(prep_stmt->from_sql);
+			values[5] = Int64GetDatumFast(prep_stmt->plansource->num_total_calls);
+			values[6] = Int64GetDatumFast(prep_stmt->plansource->num_custom_plans);
+			values[7] = Int64GetDatumFast(prep_stmt->plansource->generation);
+			if (prep_stmt->plansource->generic_cost >= 0.0)
+				values[8] = Float8GetDatum(prep_stmt->plansource->generic_cost);
+			else
+				nulls[8] = true;
+
+			if (prep_stmt->plansource->num_custom_plans > 0)
+				values[9] =
+					Float8GetDatum(prep_stmt->plansource->total_custom_cost /
+								   prep_stmt->plansource->num_custom_plans);
+			else
+				nulls[9] = true;
+
+			if (prep_stmt->plansource->last_plan_type == PLAN_CACHE_TYPE_CUSTOM)
+				values[10] = CStringGetTextDatum("custom");
+			else if (prep_stmt->plansource->last_plan_type == PLAN_CACHE_TYPE_GENERIC)
+				values[10] = CStringGetTextDatum("generic");
+			else
+				nulls[10] = true;
 
 			tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 		}
diff --git a/src/backend/utils/cache/plancache.c b/src/backend/utils/cache/plancache.c
index 75b475c..6457fcc 100644
--- a/src/backend/utils/cache/plancache.c
+++ b/src/backend/utils/cache/plancache.c
@@ -219,6 +219,7 @@ CreateCachedPlan(RawStmt *raw_parse_tree,
 	plansource->generic_cost = -1;
 	plansource->total_custom_cost = 0;
 	plansource->num_custom_plans = 0;
+	plansource->last_plan_type = PLAN_CACHE_TYPE_NONE;
 
 	MemoryContextSwitchTo(oldcxt);
 
@@ -286,6 +287,8 @@ CreateOneShotCachedPlan(RawStmt *raw_parse_tree,
 	plansource->generic_cost = -1;
 	plansource->total_custom_cost = 0;
 	plansource->num_custom_plans = 0;
+	plansource->num_total_calls = 0;
+	plansource->last_plan_type = PLAN_CACHE_TYPE_NONE;
 
 	return plansource;
 }
@@ -1213,13 +1216,15 @@ GetCachedPlan(CachedPlanSource *plansource, ParamListInfo boundParams,
 	{
 		/* Build a custom plan */
 		plan = BuildCachedPlan(plansource, qlist, boundParams, queryEnv);
-		/* Accumulate total costs of custom plans, but 'ware overflow */
-		if (plansource->num_custom_plans < INT_MAX)
-		{
-			plansource->total_custom_cost += cached_plan_cost(plan, true);
-			plansource->num_custom_plans++;
-		}
+		/* Accumulate total costs of custom plans */
+		plansource->total_custom_cost += cached_plan_cost(plan, true);
+		plansource->num_custom_plans++;
+		plansource->last_plan_type = PLAN_CACHE_TYPE_CUSTOM;
 	}
+	else
+		plansource->last_plan_type = PLAN_CACHE_TYPE_GENERIC;
+
+	plansource->num_total_calls++;
 
 	Assert(plan != NULL);
 
@@ -1575,6 +1580,10 @@ CopyCachedPlan(CachedPlanSource *plansource)
 	newsource->generic_cost = plansource->generic_cost;
 	newsource->total_custom_cost = plansource->total_custom_cost;
 	newsource->num_custom_plans = plansource->num_custom_plans;
+	newsource->num_total_calls = plansource->num_total_calls;
+
+	/* XXX: Should inherit original plansource? */
+	newsource->last_plan_type = PLAN_CACHE_TYPE_NONE;
 
 	MemoryContextSwitchTo(oldcxt);
 
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 4bce3ad..52add8d 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -7745,9 +7745,9 @@
 { oid => '2510', descr => 'get the prepared statements for this session',
   proname => 'pg_prepared_statement', prorows => '1000', proretset => 't',
   provolatile => 's', proparallel => 'r', prorettype => 'record',
-  proargtypes => '', proallargtypes => '{text,text,timestamptz,_regtype,bool}',
-  proargmodes => '{o,o,o,o,o}',
-  proargnames => '{name,statement,prepare_time,parameter_types,from_sql}',
+  proargtypes => '', proallargtypes => '{text,text,timestamptz,_regtype,bool,int8,int8,int8,float8,float8,text}',
+  proargmodes => '{o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{name,statement,prepare_time,parameter_types,from_sql,calls,custom_calls,plan_generation,generic_cost,custom_cost,last_plan}',
   prosrc => 'pg_prepared_statement' },
 { oid => '2511', descr => 'get the open cursors for this session',
   proname => 'pg_cursor', prorows => '1000', proretset => 't',
diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h
index 522020d..32c86ec 100644
--- a/src/include/utils/plancache.h
+++ b/src/include/utils/plancache.h
@@ -34,6 +34,13 @@ typedef enum
 	PLAN_CACHE_MODE_FORCE_CUSTOM_PLAN
 }			PlanCacheMode;
 
+typedef enum
+{
+	PLAN_CACHE_TYPE_NONE,
+	PLAN_CACHE_TYPE_CUSTOM,
+	PLAN_CACHE_TYPE_GENERIC
+}	PlanCacheType;
+
 /* GUC parameter */
 extern int	plan_cache_mode;
 
@@ -124,13 +131,15 @@ typedef struct CachedPlanSource
 	bool		is_complete;	/* has CompleteCachedPlan been done? */
 	bool		is_saved;		/* has CachedPlanSource been "saved"? */
 	bool		is_valid;		/* is the query_list currently valid? */
-	int			generation;		/* increments each time we create a plan */
+	int64		generation;		/* increments each time we create a plan */
 	/* If CachedPlanSource has been saved, it is a member of a global list */
 	dlist_node	node;			/* list link, if is_saved */
 	/* State kept to help decide whether to use custom or generic plans: */
 	double		generic_cost;	/* cost of generic plan, or -1 if not known */
 	double		total_custom_cost;	/* total cost of custom plans so far */
-	int			num_custom_plans;	/* number of plans included in total */
+	int64		num_custom_plans;	/* # of custom plans included in total */
+	int64		num_total_calls;/* total number of execution */
+	PlanCacheType	last_plan_type;		/* type of last plan */
 } CachedPlanSource;
 
 /*
diff --git a/src/test/regress/expected/prepare.out b/src/test/regress/expected/prepare.out
index 3306c69..e92ce6b 100644
--- a/src/test/regress/expected/prepare.out
+++ b/src/test/regress/expected/prepare.out
@@ -64,6 +64,49 @@ EXECUTE q2('postgres');
  postgres | f             | t
 (1 row)
 
+EXECUTE q2('postgres');
+ datname  | datistemplate | datallowconn 
+----------+---------------+--------------
+ postgres | f             | t
+(1 row)
+
+EXECUTE q2('postgres');
+ datname  | datistemplate | datallowconn 
+----------+---------------+--------------
+ postgres | f             | t
+(1 row)
+
+EXECUTE q2('postgres');
+ datname  | datistemplate | datallowconn 
+----------+---------------+--------------
+ postgres | f             | t
+(1 row)
+
+EXECUTE q2('postgres');
+ datname  | datistemplate | datallowconn 
+----------+---------------+--------------
+ postgres | f             | t
+(1 row)
+
+EXECUTE q2('postgres');
+ datname  | datistemplate | datallowconn 
+----------+---------------+--------------
+ postgres | f             | t
+(1 row)
+
+EXECUTE q2('postgres');
+ datname  | datistemplate | datallowconn 
+----------+---------------+--------------
+ postgres | f             | t
+(1 row)
+
+-- the view should return the correct counts
+SELECT name, calls, custom_calls, plan_generation, last_plan FROM pg_prepared_statements;
+ name | calls | custom_calls | plan_generation | last_plan 
+------+-------+--------------+-----------------+-----------
+ q2   |     7 |            5 |               6 | generic
+(1 row)
+
 PREPARE q3(text, int, float, boolean, smallint) AS
 	SELECT * FROM tenk1 WHERE string4 = $1 AND (four = $2 OR
 	ten = $3::bigint OR true = $4 OR odd = $5::int)
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 8876025..adedd01 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1428,8 +1428,14 @@ pg_prepared_statements| SELECT p.name,
     p.statement,
     p.prepare_time,
     p.parameter_types,
-    p.from_sql
-   FROM pg_prepared_statement() p(name, statement, prepare_time, parameter_types, from_sql);
+    p.from_sql,
+    p.calls,
+    p.custom_calls,
+    p.plan_generation,
+    p.generic_cost,
+    p.custom_cost,
+    p.last_plan
+   FROM pg_prepared_statement() p(name, statement, prepare_time, parameter_types, from_sql, calls, custom_calls, plan_generation, generic_cost, custom_cost, last_plan);
 pg_prepared_xacts| SELECT p.transaction,
     p.gid,
     p.prepared,
diff --git a/src/test/regress/sql/prepare.sql b/src/test/regress/sql/prepare.sql
index 985d0f0..c886558 100644
--- a/src/test/regress/sql/prepare.sql
+++ b/src/test/regress/sql/prepare.sql
@@ -35,6 +35,15 @@ PREPARE q2(text) AS
 	FROM pg_database WHERE datname = $1;
 
 EXECUTE q2('postgres');
+EXECUTE q2('postgres');
+EXECUTE q2('postgres');
+EXECUTE q2('postgres');
+EXECUTE q2('postgres');
+EXECUTE q2('postgres');
+EXECUTE q2('postgres');
+
+-- the view should return the correct counts
+SELECT name, calls, custom_calls, plan_generation, last_plan FROM pg_prepared_statements;
 
 PREPARE q3(text, int, float, boolean, smallint) AS
 	SELECT * FROM tenk1 WHERE string4 = $1 AND (four = $2 OR