Introduce clauselist_selectivity_hook

Author: danolivo

contrib/Makefile

@@ -6,6 +6,7 @@ include $(top_builddir)/src/Makefile.global
 
 SUBDIRS = \
 		amcheck		\
+		pg_index_stats	\
 		auth_delay	\
 		auto_explain	\
 		basic_archive	\

src/backend/optimizer/path/clausesel.c

@@ -128,6 +128,11 @@ clauselist_selectivity_ext(PlannerInfo *root,
 	ListCell   *l;
 	int			listidx;
 
+	if (clauselist_selectivity_hook)
+		s1 = clauselist_selectivity_hook(root, clauses, varRelid, jointype,
+										 sjinfo, &estimatedclauses,
+										 use_extended_stats);
+
 	/*
 	 * If there's exactly one clause, just go directly to
 	 * clause_selectivity_ext(). None of what we might do below is relevant.

src/backend/statistics/extended_stats.c

@@ -1712,7 +1712,7 @@ statext_is_compatible_clause(PlannerInfo *root, Node *clause, Index relid,
  * 0-based 'clauses' indexes we estimate for and also skip clause items that
  * already have a bit set.
  */
-static Selectivity
+Selectivity
 statext_mcv_clauselist_selectivity(PlannerInfo *root, List *clauses, int varRelid,
 								   JoinType jointype, SpecialJoinInfo *sjinfo,
 								   RelOptInfo *rel, Bitmapset **estimatedclauses,

src/backend/utils/adt/selfuncs.c

@@ -146,6 +146,7 @@
 /* Hooks for plugins to get control when we ask for stats */
 get_relation_stats_hook_type get_relation_stats_hook = NULL;
 get_index_stats_hook_type get_index_stats_hook = NULL;
+clauselist_selectivity_hook_type clauselist_selectivity_hook = NULL;
 
 static double eqsel_internal(PG_FUNCTION_ARGS, bool negate);
 static double eqjoinsel_inner(Oid opfuncoid, Oid collation,

src/include/statistics/statistics.h

@@ -104,6 +104,14 @@ extern void BuildRelationExtStatistics(Relation onerel, bool inh, double totalro
 extern int	ComputeExtStatisticsRows(Relation onerel,
 									 int natts, VacAttrStats **vacattrstats);
 extern bool statext_is_kind_built(HeapTuple htup, char type);
+extern Selectivity statext_mcv_clauselist_selectivity(PlannerInfo *root,
+													  List *clauses,
+													  int varRelid,
+													  JoinType jointype,
+													  SpecialJoinInfo *sjinfo,
+													   RelOptInfo *rel,
+													   Bitmapset **estimatedclauses,
+													   bool is_or);
 extern Selectivity dependencies_clauselist_selectivity(PlannerInfo *root,
 													   List *clauses,
 													   int varRelid,

src/include/utils/selfuncs.h

@@ -148,6 +148,17 @@ typedef bool (*get_index_stats_hook_type) (PlannerInfo *root,
 										   VariableStatData *vardata);
 extern PGDLLIMPORT get_index_stats_hook_type get_index_stats_hook;
 
+/* Hooks for plugins to get control when we ask for selectivity estimation */
+typedef Selectivity (*clauselist_selectivity_hook_type) (
+												PlannerInfo *root,
+												List *clauses,
+												int varRelid,
+												JoinType jointype,
+												SpecialJoinInfo *sjinfo,
+												Bitmapset **estimatedclauses,
+												bool use_extended_stats);
+extern PGDLLIMPORT clauselist_selectivity_hook_type clauselist_selectivity_hook;
+
 /* Functions in selfuncs.c */
 
 extern void examine_variable(PlannerInfo *root, Node *node, int varRelid,