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Support for INCLUDE attributes in GiST indexes

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Similarly to B-tree, GiST index access method gets support of INCLUDE
attributes.  These attributes aren't used for tree navigation and aren't
present in non-leaf pages.  But they are present in leaf pages and can be
fetched during index-only scan.

The point of having INCLUDE attributes in GiST indexes is slightly different
from the point of having them in B-tree.  The main point of INCLUDE attributes
in B-tree is to define UNIQUE constraint over part of attributes enabled for
index-only scan.  In GiST the main point of INCLUDE attributes is to use
index-only scan for attributes, whose data types don't have GiST opclasses.

Discussion: https://postgr.es/m/73A1A452-AD5F-40D4-BD61-978622FF75C1%40yandex-team.ru
Author: Andrey Borodin, with small changes by me
Reviewed-by: Andreas Karlsson
This commit is contained in:
Alexander Korotkov
2019-03-10 11:36:47 +03:00
parent a0b7626268
commit f2e403803f
16 changed files with 382 additions and 48 deletions
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13
src/backend/access/gist/gistscan.c
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@ -158,6 +158,7 @@ gistrescan(IndexScanDesc scan, ScanKey key, int nkeys,
if (scan->xs_want_itup && !scan->xs_hitupdesc)
{
int natts;
int nkeyatts;
int attno;
/*
@ -167,13 +168,23 @@ gistrescan(IndexScanDesc scan, ScanKey key, int nkeys,
* types.
*/
natts = RelationGetNumberOfAttributes(scan->indexRelation);
nkeyatts = IndexRelationGetNumberOfKeyAttributes(scan->indexRelation);
so->giststate->fetchTupdesc = CreateTemplateTupleDesc(natts);
for (attno = 1; attno <= natts; attno++)
for (attno = 1; attno <= nkeyatts; attno++)
{
TupleDescInitEntry(so->giststate->fetchTupdesc, attno, NULL,
scan->indexRelation->rd_opcintype[attno - 1],
-1, 0);
}
for (; attno <= natts; attno++)
{
/* taking opcintype from giststate->tupdesc */
TupleDescInitEntry(so->giststate->fetchTupdesc, attno, NULL,
TupleDescAttr(so->giststate->leafTupdesc,
attno - 1)->atttypid,
-1, 0);
}
scan->xs_hitupdesc = so->giststate->fetchTupdesc;
/* Also create a memory context that will hold the returned tuples */