0001-Only-acquire-KEY-LOCK-for-colums-that-can-be-referen.patch

From e069cef91c686aa87e220336198267e5a5a2aeac Mon Sep 17 00:00:00 2001
From: Marti Raudsepp <marti@juffo.org>
Date: Tue, 15 Feb 2011 00:33:35 +0200
Subject: [PATCH] Only acquire KEY LOCK for colums that can be referenced by foreign keys

Don't consider columns in unique indexes that have expressions or WHERE
predicates.
---
 src/backend/utils/cache/relcache.c |   23 +++++++++++++----------
 src/include/utils/rel.h            |    2 +-
 src/include/utils/relcache.h       |    2 +-
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 4d37e8e..5119288 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -3608,7 +3608,8 @@ RelationGetIndexPredicate(Relation relation)
  * simple index keys, but attributes used in expressions and partial-index
  * predicates.)
  *
- * If "unique" is true, only attributes of unique indexes are considered.
+ * If "keyAttrs" is true, only attributes that can be referenced by foreign
+ * keys are considered.
  *
  * Attribute numbers are offset by FirstLowInvalidHeapAttributeNumber so that
  * we can include system attributes (e.g., OID) in the bitmap representation.
@@ -3617,7 +3618,7 @@ RelationGetIndexPredicate(Relation relation)
  * be bms_free'd when not needed anymore.
  */
 Bitmapset *
-RelationGetIndexAttrBitmap(Relation relation, bool unique)
+RelationGetIndexAttrBitmap(Relation relation, bool keyAttrs)
 {
 	Bitmapset  *indexattrs;
 	Bitmapset  *uindexattrs;
@@ -3627,7 +3628,7 @@ RelationGetIndexAttrBitmap(Relation relation, bool unique)
 
 	/* Quick exit if we already computed the result. */
 	if (relation->rd_indexattr != NULL)
-		return bms_copy(unique ? relation->rd_uindexattr : relation->rd_indexattr);
+		return bms_copy(keyAttrs ? relation->rd_keyattr : relation->rd_indexattr);
 
 	/* Fast path if definitely no indexes */
 	if (!RelationGetForm(relation)->relhasindex)
@@ -3653,12 +3654,18 @@ RelationGetIndexAttrBitmap(Relation relation, bool unique)
 		Relation	indexDesc;
 		IndexInfo  *indexInfo;
 		int			i;
+		bool		isKey;
 
 		indexDesc = index_open(indexOid, AccessShareLock);
 
 		/* Extract index key information from the index's pg_index row */
 		indexInfo = BuildIndexInfo(indexDesc);
 
+		/* Can this index be referenced by a foreign key? */
+		isKey = indexInfo->ii_Unique &&
+				indexInfo->ii_Expressions == NIL &&
+				indexInfo->ii_Predicate == NIL;
+
 		/* Collect simple attribute references */
 		for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
 		{
@@ -3668,7 +3675,7 @@ RelationGetIndexAttrBitmap(Relation relation, bool unique)
 			{
 				indexattrs = bms_add_member(indexattrs,
 							   attrnum - FirstLowInvalidHeapAttributeNumber);
-				if (indexInfo->ii_Unique)
+				if (isKey)
 					uindexattrs = bms_add_member(uindexattrs,
 											   	 attrnum - FirstLowInvalidHeapAttributeNumber);
 			}
@@ -3676,13 +3683,9 @@ RelationGetIndexAttrBitmap(Relation relation, bool unique)
 
 		/* Collect all attributes used in expressions, too */
 		pull_varattnos((Node *) indexInfo->ii_Expressions, &indexattrs);
-		if (indexInfo->ii_Unique)
-			pull_varattnos((Node *) indexInfo->ii_Expressions, &uindexattrs);
 
 		/* Collect all attributes in the index predicate, too */
 		pull_varattnos((Node *) indexInfo->ii_Predicate, &indexattrs);
-		if (indexInfo->ii_Unique)
-			pull_varattnos((Node *) indexInfo->ii_Predicate, &uindexattrs);
 
 		index_close(indexDesc, AccessShareLock);
 	}
@@ -3692,11 +3695,11 @@ RelationGetIndexAttrBitmap(Relation relation, bool unique)
 	/* Now save a copy of the bitmap in the relcache entry. */
 	oldcxt = MemoryContextSwitchTo(CacheMemoryContext);
 	relation->rd_indexattr = bms_copy(indexattrs);
-	relation->rd_uindexattr = bms_copy(uindexattrs);
+	relation->rd_keyattr = bms_copy(uindexattrs);
 	MemoryContextSwitchTo(oldcxt);
 
 	/* We return our original working copy for caller to play with */
-	return unique ? uindexattrs : indexattrs;
+	return keyAttrs ? uindexattrs : indexattrs;
 }
 
 /*
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 2251b25..9b70d81 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -156,7 +156,7 @@ typedef struct RelationData
 	Oid			rd_id;			/* relation's object id */
 	List	   *rd_indexlist;	/* list of OIDs of indexes on relation */
 	Bitmapset  *rd_indexattr;	/* identifies columns used in indexes */
-	Bitmapset  *rd_uindexattr;	/* identifies columns used in unique indexes */
+	Bitmapset  *rd_keyattr;		/* cols that can be ref'd by foreign keys */
 	Oid			rd_oidindex;	/* OID of unique index on OID, if any */
 	LockInfoData rd_lockInfo;	/* lock mgr's info for locking relation */
 	RuleLock   *rd_rules;		/* rewrite rules */
diff --git a/src/include/utils/relcache.h b/src/include/utils/relcache.h
index 6d1e64f..d4a09e3 100644
--- a/src/include/utils/relcache.h
+++ b/src/include/utils/relcache.h
@@ -42,7 +42,7 @@ extern List *RelationGetIndexList(Relation relation);
 extern Oid	RelationGetOidIndex(Relation relation);
 extern List *RelationGetIndexExpressions(Relation relation);
 extern List *RelationGetIndexPredicate(Relation relation);
-extern Bitmapset *RelationGetIndexAttrBitmap(Relation relation, bool unique);
+extern Bitmapset *RelationGetIndexAttrBitmap(Relation relation, bool keyAttrs);
 extern void RelationGetExclusionInfo(Relation indexRelation,
 						 Oid **operators,
 						 Oid **procs,
-- 
1.7.4