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/nodes/copyfuncs.c | 29 ++++++++++++++++++++++++++++- 1 file changed, 28 insertions(+), 1 deletion(-) (limited to 'src/backend/nodes/copyfuncs.c') diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c index 5100642dd63..24ac5295f60 100644 --- a/src/backend/nodes/copyfuncs.c +++ b/src/backend/nodes/copyfuncs.c @@ -370,7 +370,31 @@ _copyIndexScan(IndexScan *from) COPY_NODE_FIELD(indexorderby); COPY_NODE_FIELD(indexorderbyorig); COPY_SCALAR_FIELD(indexorderdir); - COPY_SCALAR_FIELD(indexonly); + + return newnode; +} + +/* + * _copyIndexOnlyScan + */ +static IndexOnlyScan * +_copyIndexOnlyScan(IndexOnlyScan *from) +{ + IndexOnlyScan *newnode = makeNode(IndexOnlyScan); + + /* + * copy node superclass fields + */ + CopyScanFields((Scan *) from, (Scan *) newnode); + + /* + * copy remainder of node + */ + COPY_SCALAR_FIELD(indexid); + COPY_NODE_FIELD(indexqual); + COPY_NODE_FIELD(indexorderby); + COPY_NODE_FIELD(indextlist); + COPY_SCALAR_FIELD(indexorderdir); return newnode; } @@ -3871,6 +3895,9 @@ copyObject(void *from) case T_IndexScan: retval = _copyIndexScan(from); break; + case T_IndexOnlyScan: + retval = _copyIndexOnlyScan(from); + break; case T_BitmapIndexScan: retval = _copyBitmapIndexScan(from); break; -- cgit v1.2.3