From a0185461dd94c8d31d8d55a7f2839b0d2f172ab9 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 11 Oct 2011 14:20:06 -0400 Subject: Rearrange the implementation of index-only scans. This commit changes index-only scans so that data is read directly from the index tuple without first generating a faux heap tuple. The only immediate benefit is that indexes on system columns (such as OID) can be used in index-only scans, but this is necessary infrastructure if we are ever to support index-only scans on expression indexes. The executor is now ready for that, though the planner still needs substantial work to recognize the possibility. To do this, Vars in index-only plan nodes have to refer to index columns not heap columns. I introduced a new special varno, INDEX_VAR, to mark such Vars to avoid confusion. (In passing, this commit renames the two existing special varnos to OUTER_VAR and INNER_VAR.) This allows ruleutils.c to handle them with logic similar to what we use for subplan reference Vars. Since index-only scans are now fundamentally different from regular indexscans so far as their expression subtrees are concerned, I also chose to change them to have their own plan node type (and hence, their own executor source file). --- src/backend/optimizer/util/pathnode.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'src/backend/optimizer/util/pathnode.c') diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index 8ed55a3d0e2..6aa34412def 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -452,7 +452,7 @@ create_index_path(PlannerInfo *root, indexscandir = NoMovementScanDirection; } - pathnode->path.pathtype = T_IndexScan; + pathnode->path.pathtype = indexonly ? T_IndexOnlyScan : T_IndexScan; pathnode->path.parent = rel; pathnode->path.pathkeys = pathkeys; @@ -470,7 +470,6 @@ create_index_path(PlannerInfo *root, pathnode->isjoininner = (outer_rel != NULL); pathnode->indexscandir = indexscandir; - pathnode->indexonly = indexonly; if (outer_rel != NULL) { -- cgit v1.2.3