CREATE INDEX ... INCLUDING (column[, ...])

Now indexes (but only B-tree for now) can contain "extra" column(s) which
doesn't participate in index structure, they are just stored in leaf
tuples. It allows to use index only scan by using single index instead
of two or more indexes.

Author: Anastasia Lubennikova with minor editorializing by me
Reviewers: David Rowley, Peter Geoghegan, Jeff Janes

1 files changed, 17 insertions, 8 deletions

diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 83c553ca279..8c5509f4a2c 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -63,17 +63,26 @@ _bt_mkscankey(Relation rel, IndexTuple itup)
 {
 	ScanKey		skey;
 	TupleDesc	itupdesc;
-	int			natts;
+	int			indnatts,
+				indnkeyatts;
 	int16	   *indoption;
 	int			i;
 
 	itupdesc = RelationGetDescr(rel);
-	natts = RelationGetNumberOfAttributes(rel);
+	indnatts = IndexRelationGetNumberOfAttributes(rel);
+	indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
 	indoption = rel->rd_indoption;
 
-	skey = (ScanKey) palloc(natts * sizeof(ScanKeyData));
+	Assert(indnkeyatts != 0);
+	Assert(indnkeyatts <= indnatts);
 
-	for (i = 0; i < natts; i++)
+	/*
+	 * We'll execute search using ScanKey constructed on key columns.
+	 * Non key (included) columns must be omitted.
+	 */
+	skey = (ScanKey) palloc(indnkeyatts * sizeof(ScanKeyData));
+
+	for (i = 0; i < indnkeyatts; i++)
 	{
 		FmgrInfo   *procinfo;
 		Datum		arg;
@@ -115,16 +124,16 @@ ScanKey
 _bt_mkscankey_nodata(Relation rel)
 {
 	ScanKey		skey;
-	int			natts;
+	int			indnkeyatts;
 	int16	   *indoption;
 	int			i;
 
-	natts = RelationGetNumberOfAttributes(rel);
+	indnkeyatts = IndexRelationGetNumberOfKeyAttributes(rel);
 	indoption = rel->rd_indoption;
 
-	skey = (ScanKey) palloc(natts * sizeof(ScanKeyData));
+	skey = (ScanKey) palloc(indnkeyatts * sizeof(ScanKeyData));
 
-	for (i = 0; i < natts; i++)
+	for (i = 0; i < indnkeyatts; i++)
 	{
 		FmgrInfo   *procinfo;
 		int			flags;