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/executor/execUtils.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'src/backend/executor/execUtils.c') diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c index 4dbf10b8da9..65591e2445d 100644 --- a/src/backend/executor/execUtils.c +++ b/src/backend/executor/execUtils.c @@ -566,20 +566,22 @@ ExecBuildProjectionInfo(List *targetList, switch (variable->varno) { - case INNER: + case INNER_VAR: varSlotOffsets[numSimpleVars] = offsetof(ExprContext, ecxt_innertuple); if (projInfo->pi_lastInnerVar < attnum) projInfo->pi_lastInnerVar = attnum; break; - case OUTER: + case OUTER_VAR: varSlotOffsets[numSimpleVars] = offsetof(ExprContext, ecxt_outertuple); if (projInfo->pi_lastOuterVar < attnum) projInfo->pi_lastOuterVar = attnum; break; + /* INDEX_VAR is handled by default case */ + default: varSlotOffsets[numSimpleVars] = offsetof(ExprContext, ecxt_scantuple); @@ -628,16 +630,18 @@ get_last_attnums(Node *node, ProjectionInfo *projInfo) switch (variable->varno) { - case INNER: + case INNER_VAR: if (projInfo->pi_lastInnerVar < attnum) projInfo->pi_lastInnerVar = attnum; break; - case OUTER: + case OUTER_VAR: if (projInfo->pi_lastOuterVar < attnum) projInfo->pi_lastOuterVar = attnum; break; + /* INDEX_VAR is handled by default case */ + default: if (projInfo->pi_lastScanVar < attnum) projInfo->pi_lastScanVar = attnum; -- cgit v1.2.3