3 files changed, 45 insertions, 11 deletions

diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h
index a081ca689a3..ec1ea102331 100644
--- a/src/include/optimizer/planmain.h
+++ b/src/include/optimizer/planmain.h
@@ -118,9 +118,11 @@ extern bool innerrel_is_unique(PlannerInfo *root,
  */
 extern Plan *set_plan_references(PlannerInfo *root, Plan *plan);
 extern void record_plan_function_dependency(PlannerInfo *root, Oid funcid);
+extern void record_plan_type_dependency(PlannerInfo *root, Oid typeid);
 extern void extract_query_dependencies(Node *query,
 						   List **relationOids,
 						   List **invalItems,
 						   bool *hasRowSecurity);
+extern bool extract_query_dependencies_walker(Node *node, PlannerInfo *root);
 
 #endif							/* PLANMAIN_H */
diff --git a/src/include/optimizer/planner.h b/src/include/optimizer/planner.h
index 3e733b34ed9..902ab403ed9 100644
--- a/src/include/optimizer/planner.h
+++ b/src/include/optimizer/planner.h
@@ -55,6 +55,9 @@ extern Path *get_cheapest_fractional_path(RelOptInfo *rel,
 							 double tuple_fraction);
 
 extern Expr *expression_planner(Expr *expr);
+extern Expr *expression_planner_with_deps(Expr *expr,
+							 List **relationOids,
+							 List **invalItems);
 
 extern Expr *preprocess_phv_expression(PlannerInfo *root, Expr *expr);
 
diff --git a/src/include/utils/plancache.h b/src/include/utils/plancache.h
index 5fc7903a068..7fd7ea6c168 100644
--- a/src/include/utils/plancache.h
+++ b/src/include/utils/plancache.h
@@ -16,14 +16,27 @@
 #define PLANCACHE_H
 
 #include "access/tupdesc.h"
+#include "lib/ilist.h"
 #include "nodes/params.h"
 #include "utils/queryenvironment.h"
 
 /* Forward declaration, to avoid including parsenodes.h here */
 struct RawStmt;
 
+/* possible values for plan_cache_mode */
+typedef enum
+{
+	PLAN_CACHE_MODE_AUTO,
+	PLAN_CACHE_MODE_FORCE_GENERIC_PLAN,
+	PLAN_CACHE_MODE_FORCE_CUSTOM_PLAN
+}			PlanCacheMode;
+
+/* GUC parameter */
+extern int	plan_cache_mode;
+
 #define CACHEDPLANSOURCE_MAGIC		195726186
 #define CACHEDPLAN_MAGIC			953717834
+#define CACHEDEXPR_MAGIC			838275847
 
 /*
  * CachedPlanSource (which might better have been called CachedQuery)
@@ -110,7 +123,7 @@ typedef struct CachedPlanSource
 	bool		is_valid;		/* is the query_list currently valid? */
 	int			generation;		/* increments each time we create a plan */
 	/* If CachedPlanSource has been saved, it is a member of a global list */
-	struct CachedPlanSource *next_saved;	/* list link, if so */
+	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 */
@@ -143,6 +156,30 @@ typedef struct CachedPlan
 	MemoryContext context;		/* context containing this CachedPlan */
 } CachedPlan;
 
+/*
+ * CachedExpression is a low-overhead mechanism for caching the planned form
+ * of standalone scalar expressions.  While such expressions are not usually
+ * subject to cache invalidation events, that can happen, for example because
+ * of replacement of a SQL function that was inlined into the expression.
+ * The plancache takes care of storing the expression tree and marking it
+ * invalid if a cache invalidation occurs, but the caller must notice the
+ * !is_valid status and discard the obsolete expression without reusing it.
+ * We do not store the original parse tree, only the planned expression;
+ * this is an optimization based on the assumption that we usually will not
+ * need to replan for the life of the session.
+ */
+typedef struct CachedExpression
+{
+	int			magic;			/* should equal CACHEDEXPR_MAGIC */
+	Node	   *expr;			/* planned form of expression */
+	bool		is_valid;		/* is the expression still valid? */
+	/* remaining fields should be treated as private to plancache.c: */
+	List	   *relationOids;	/* OIDs of relations the expr depends on */
+	List	   *invalItems;		/* other dependencies, as PlanInvalItems */
+	MemoryContext context;		/* context containing this CachedExpression */
+	dlist_node	node;			/* link in global list of CachedExpressions */
+} CachedExpression;
+
 
 extern void InitPlanCache(void);
 extern void ResetPlanCache(void);
@@ -182,15 +219,7 @@ extern CachedPlan *GetCachedPlan(CachedPlanSource *plansource,
 			  QueryEnvironment *queryEnv);
 extern void ReleaseCachedPlan(CachedPlan *plan, bool useResOwner);
 
-/* possible values for plan_cache_mode */
-typedef enum
-{
-	PLAN_CACHE_MODE_AUTO,
-	PLAN_CACHE_MODE_FORCE_GENERIC_PLAN,
-	PLAN_CACHE_MODE_FORCE_CUSTOM_PLAN
-}			PlanCacheMode;
-
-/* GUC parameter */
-extern int plan_cache_mode;
+extern CachedExpression *GetCachedExpression(Node *expr);
+extern void FreeCachedExpression(CachedExpression *cexpr);
 
 #endif							/* PLANCACHE_H */