Revert "Use Foreign Key relationships to infer multi-column join selectivity".

This commit reverts 137805f89 as well as the associated commits 015e88942,
5306df283, and 68d704edb.  We found multiple bugs in this feature, and
there was concern about possible planner slowdown (though to be fair,
exhibiting a very large slowdown proved difficult).  The way forward
requires a considerable rewrite, which may or may not be possible to
accomplish in time for beta2.  In my judgment reviewing the rewrite will
be easier to accomplish starting from a clean slate, so let's temporarily
revert what's there now.  This also leaves us in a safe state if it turns
out to be necessary to postpone the rewrite to the next development cycle.

Discussion: <20160429102531.GA13701@huehner.biz>

6 files changed, 0 insertions, 30 deletions

diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index ea65f2e453b..5953db45a89 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -223,7 +223,6 @@ typedef enum NodeTag
 	T_PlannerGlobal,
 	T_RelOptInfo,
 	T_IndexOptInfo,
-	T_ForeignKeyOptInfo,
 	T_ParamPathInfo,
 	T_Path,
 	T_IndexPath,
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 45739c3ee7a..b1f6cf45f0b 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -516,7 +516,6 @@ typedef struct RelOptInfo
 	List	   *lateral_vars;	/* LATERAL Vars and PHVs referenced by rel */
 	Relids		lateral_referencers;	/* rels that reference me laterally */
 	List	   *indexlist;		/* list of IndexOptInfo */
-	List	   *fkeylist;			/* list of ForeignKeyOptInfo */
 	BlockNumber pages;			/* size estimates derived from pg_class */
 	double		tuples;
 	double		allvisfrac;
@@ -623,27 +622,6 @@ typedef struct IndexOptInfo
 	void		(*amcostestimate) ();	/* AM's cost estimator */
 } IndexOptInfo;
 
-/*
- * ForeignKeyOptInfo
- *		Per-foreign-key information for planning/optimization
- *
- * Only includes columns from pg_constraint related to foreign keys.
- *
- * conkeys[], confkeys[] and conpfeqop[] each have nkeys entries.
- */
-typedef struct ForeignKeyOptInfo
-{
-	NodeTag		type;
-
-	Oid			conrelid;	/* relation constrained by the foreign key */
-	Oid			confrelid;	/* relation referenced by the foreign key */
-
-	int			nkeys;		/* number of columns in the foreign key */
-	int		   *conkeys;	/* attnums of columns in the constrained table */
-	int		   *confkeys;	/* attnums of columns in the referenced table */
-	Oid		   *conpfeqop;	/* OIDs of equality operators used by the FK */
-
-} ForeignKeyOptInfo;
 
 /*
  * EquivalenceClasses
diff --git a/src/include/optimizer/cost.h b/src/include/optimizer/cost.h
index 58ac1638ec1..d4adca6836a 100644
--- a/src/include/optimizer/cost.h
+++ b/src/include/optimizer/cost.h
@@ -66,7 +66,6 @@ extern bool enable_nestloop;
 extern bool enable_material;
 extern bool enable_mergejoin;
 extern bool enable_hashjoin;
-extern bool enable_fkey_estimates;
 extern int	constraint_exclusion;
 
 extern double clamp_row_est(double nrows);
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h
index e0ac4515c95..f3b25e2419c 100644
--- a/src/include/optimizer/paths.h
+++ b/src/include/optimizer/paths.h
@@ -76,8 +76,6 @@ extern Expr *adjust_rowcompare_for_index(RowCompareExpr *clause,
 							int indexcol,
 							List **indexcolnos,
 							bool *var_on_left_p);
-extern bool has_matching_fkey(RelOptInfo *rel, RelOptInfo *frel, List *clauses,
-							  bool reverse);
 
 /*
  * tidpath.h
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index a0ba4177645..5d354c0f67b 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -95,9 +95,6 @@ typedef struct RelationData
 	Oid			rd_oidindex;	/* OID of unique index on OID, if any */
 	Oid			rd_replidindex; /* OID of replica identity index, if any */
 
-	/* data managed by RelationGetFKList: */
-	List	   *rd_fkeylist;		/* OIDs of foreign keys */
-
 	/* data managed by RelationGetIndexAttrBitmap: */
 	Bitmapset  *rd_indexattr;	/* identifies columns used in indexes */
 	Bitmapset  *rd_keyattr;		/* cols that can be ref'd by foreign keys */
diff --git a/src/include/utils/relcache.h b/src/include/utils/relcache.h
index 7f07c269145..1b4830462d5 100644
--- a/src/include/utils/relcache.h
+++ b/src/include/utils/relcache.h
@@ -38,7 +38,6 @@ extern void RelationClose(Relation relation);
  * Routines to compute/retrieve additional cached information
  */
 extern List *RelationGetIndexList(Relation relation);
-extern List *RelationGetFKeyList(Relation relation);
 extern Oid	RelationGetOidIndex(Relation relation);
 extern Oid	RelationGetReplicaIndex(Relation relation);
 extern List *RelationGetIndexExpressions(Relation relation);