database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-17 01:02:17 +03:00
Code Activity

Indexes with INCLUDE columns and their support in B-tree

Browse Source 
This patch introduces INCLUDE clause to index definition.  This clause
specifies a list of columns which will be included as a non-key part in
the index.  The INCLUDE columns exist solely to allow more queries to
benefit from index-only scans.  Also, such columns don't need to have
appropriate operator classes.  Expressions are not supported as INCLUDE
columns since they cannot be used in index-only scans.

Index access methods supporting INCLUDE are indicated by amcaninclude flag
in IndexAmRoutine.  For now, only B-tree indexes support INCLUDE clause.

In B-tree indexes INCLUDE columns are truncated from pivot index tuples
(tuples located in non-leaf pages and high keys).  Therefore, B-tree indexes
now might have variable number of attributes.  This patch also provides
generic facility to support that: pivot tuples contain number of their
attributes in t_tid.ip_posid.  Free 13th bit of t_info is used for indicating
that.  This facility will simplify further support of index suffix truncation.
The changes of above are backward-compatible, pg_upgrade doesn't need special
handling of B-tree indexes for that.

Bump catalog version

Author: Anastasia Lubennikova with contribition by Alexander Korotkov and me
Reviewed by: Peter Geoghegan, Tomas Vondra, Antonin Houska, Jeff Janes,
			 David Rowley, Alexander Korotkov
Discussion: https://www.postgresql.org/message-id/flat/56168952.4010101@postgrespro.ru
This commit is contained in:
Teodor Sigaev
2018-04-07 23:00:39 +03:00
parent 01bb85169a
commit 8224de4f42
89 changed files with 2112 additions and 467 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
src/backend/access/common/indextuple.c
View File

@@ -19,6 +19,7 @@
#include "access/heapam.h"
#include "access/itup.h"
#include "access/tuptoaster.h"
#include "utils/rel.h"
/* ----------------------------------------------------------------
@@ -445,3 +446,33 @@ CopyIndexTuple(IndexTuple source)
memcpy(result, source, size);
return result;
}
/*
* Truncate tailing attributes from given index tuple leaving it with
* new_indnatts number of attributes.
*/
IndexTuple
index_truncate_tuple(TupleDesc tupleDescriptor, IndexTuple olditup,
int new_indnatts)
{
TupleDesc itupdesc = CreateTupleDescCopyConstr(tupleDescriptor);
Datum values[INDEX_MAX_KEYS];
bool isnull[INDEX_MAX_KEYS];
IndexTuple newitup;
int indnatts = tupleDescriptor->natts;
Assert(indnatts <= INDEX_MAX_KEYS);
Assert(new_indnatts > 0);
Assert(new_indnatts < indnatts);
index_deform_tuple(olditup, tupleDescriptor, values, isnull);
/* form new tuple that will contain only key attributes */
itupdesc->natts = new_indnatts;
newitup = index_form_tuple(itupdesc, values, isnull);
newitup->t_tid = olditup->t_tid;
FreeTupleDesc(itupdesc);
Assert(IndexTupleSize(newitup) <= IndexTupleSize(olditup));
return newitup;
}