From 8224de4f42ccf98e08db07b43d52fed72f962ebb Mon Sep 17 00:00:00 2001 From: Teodor Sigaev Date: Sat, 7 Apr 2018 23:00:39 +0300 Subject: Indexes with INCLUDE columns and their support in B-tree 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 --- src/backend/access/common/indextuple.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'src/backend/access/common/indextuple.c') diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c index f7103e53bcc..a9c0b620ec0 100644 --- a/src/backend/access/common/indextuple.c +++ b/src/backend/access/common/indextuple.c @@ -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; +} -- cgit v1.2.3