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/execQual.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) (limited to 'src/backend/executor/execQual.c') diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c index 80f08d8b92e..887e5ce82a0 100644 --- a/src/backend/executor/execQual.c +++ b/src/backend/executor/execQual.c @@ -578,14 +578,16 @@ ExecEvalVar(ExprState *exprstate, ExprContext *econtext, /* Get the input slot and attribute number we want */ switch (variable->varno) { - case INNER: /* get the tuple from the inner node */ + case INNER_VAR: /* get the tuple from the inner node */ slot = econtext->ecxt_innertuple; break; - case OUTER: /* get the tuple from the outer node */ + case OUTER_VAR: /* get the tuple from the outer node */ slot = econtext->ecxt_outertuple; break; + /* INDEX_VAR is handled by default case */ + default: /* get the tuple from the relation being * scanned */ slot = econtext->ecxt_scantuple; @@ -761,14 +763,16 @@ ExecEvalScalarVar(ExprState *exprstate, ExprContext *econtext, /* Get the input slot and attribute number we want */ switch (variable->varno) { - case INNER: /* get the tuple from the inner node */ + case INNER_VAR: /* get the tuple from the inner node */ slot = econtext->ecxt_innertuple; break; - case OUTER: /* get the tuple from the outer node */ + case OUTER_VAR: /* get the tuple from the outer node */ slot = econtext->ecxt_outertuple; break; + /* INDEX_VAR is handled by default case */ + default: /* get the tuple from the relation being * scanned */ slot = econtext->ecxt_scantuple; @@ -804,14 +808,16 @@ ExecEvalWholeRowVar(ExprState *exprstate, ExprContext *econtext, /* Get the input slot we want */ switch (variable->varno) { - case INNER: /* get the tuple from the inner node */ + case INNER_VAR: /* get the tuple from the inner node */ slot = econtext->ecxt_innertuple; break; - case OUTER: /* get the tuple from the outer node */ + case OUTER_VAR: /* get the tuple from the outer node */ slot = econtext->ecxt_outertuple; break; + /* INDEX_VAR is handled by default case */ + default: /* get the tuple from the relation being * scanned */ slot = econtext->ecxt_scantuple; @@ -873,14 +879,16 @@ ExecEvalWholeRowSlow(ExprState *exprstate, ExprContext *econtext, /* Get the input slot we want */ switch (variable->varno) { - case INNER: /* get the tuple from the inner node */ + case INNER_VAR: /* get the tuple from the inner node */ slot = econtext->ecxt_innertuple; break; - case OUTER: /* get the tuple from the outer node */ + case OUTER_VAR: /* get the tuple from the outer node */ slot = econtext->ecxt_outertuple; break; + /* INDEX_VAR is handled by default case */ + default: /* get the tuple from the relation being * scanned */ slot = econtext->ecxt_scantuple; -- cgit v1.2.3