diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index d263ecf082..94f7993529 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -26,6 +26,9 @@
 #include "utils/lsyscache.h"
 #include "utils/selfuncs.h"
 
+/* Hooks for plugins to get control when we ask for selectivity */
+clauselist_selectivity_hook_type clauselist_selectivity_hook = NULL;
+
 /*
  * Data structure for accumulating info about possible range-query
  * clause pairs in clauselist_selectivity.
@@ -130,6 +133,18 @@ clauselist_selectivity_ext(PlannerInfo *root,
 	ListCell   *l;
 	int			listidx;
 
+	/*
+	* If we have a hook for selectivity estimation and it returns True, then go for it.
+	*/
+	if (clauselist_selectivity_hook && 
+		(*clauselist_selectivity_hook) (root, clauses, varRelid, jointype, sjinfo, use_extended_stats, &s1))
+		{
+			/*
+			* The hook takes control of estimating the selectivity
+			* and saves the estimated selectivity to s1.
+			*/
+			return s1;
+		}
 	/*
 	 * If there's exactly one clause, just go directly to
 	 * clause_selectivity_ext(). None of what we might do below is relevant.
@@ -370,7 +385,19 @@ clauselist_selectivity_or(PlannerInfo *root,
 	Bitmapset  *estimatedclauses = NULL;
 	ListCell   *lc;
 	int			listidx;
-
+	
+	/*
+	 * If we have a hook for selectivity estimation and it returns True, then go for it.
+	 */
+	if (clauselist_selectivity_hook && 
+		(*clauselist_selectivity_hook) (root, clauses, varRelid, jointype, sjinfo, use_extended_stats, &s1))
+		{
+			/*
+			* The hook takes control of estimating the selectivity
+			* and saves the estimated selectivity to s1.
+			*/
+			return s1;
+		}
 	/*
 	 * Determine if these clauses reference a single relation.  If so, and if
 	 * it has extended statistics, try to apply those.
diff --git a/src/include/optimizer/optimizer.h b/src/include/optimizer/optimizer.h
index 41b49b2662..7e10144822 100644
--- a/src/include/optimizer/optimizer.h
+++ b/src/include/optimizer/optimizer.h
@@ -202,4 +202,17 @@ extern int	locate_var_of_level(Node *node, int levelsup);
 extern List *pull_var_clause(Node *node, int flags);
 extern Node *flatten_join_alias_vars(Query *query, Node *node);
 
+/* Hooks for external selectivity estimation */
+typedef bool (*clauselist_selectivity_hook_type) (
+						   PlannerInfo *root,
+						   List *clauses,
+						   int varRelid,
+						   JoinType jointype,
+						   SpecialJoinInfo *sjinfo,
+						   bool use_extended_stats,
+						   Selectivity *s);
+
+extern PGDLLIMPORT clauselist_selectivity_hook_type clauselist_selectivity_hook;
+
+
 #endif							/* OPTIMIZER_H */