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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-11 14:20:06 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2011-10-11 14:21:30 -0400 |
| commit | a0185461dd94c8d31d8d55a7f2839b0d2f172ab9 (patch) | |
| tree | 3bd68d4e123336bbdefa8fd92372f0af7fb6d64f /src/backend/executor/execQual.c | |
| parent | fa351d5a0db0672b6f586315720302e493116f27 (diff) | |
| download | postgresql-a0185461dd94c8d31d8d55a7f2839b0d2f172ab9.tar.gz postgresql-a0185461dd94c8d31d8d55a7f2839b0d2f172ab9.zip | |
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).
Diffstat (limited to 'src/backend/executor/execQual.c')
| -rw-r--r-- | src/backend/executor/execQual.c | 24 |
1 files changed, 16 insertions, 8 deletions
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; |