database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-11 10:01:57 +03:00
Code Activity

Rearrange the implementation of index-only scans.

Browse Source 
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).
This commit is contained in:
Tom Lane
2011-10-11 14:20:06 -04:00
parent fa351d5a0d
commit a0185461dd
34 changed files with 1312 additions and 419 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
src/backend/nodes/outfuncs.c
View File

@ -447,7 +447,20 @@ _outIndexScan(StringInfo str, IndexScan *node)
WRITE_NODE_FIELD(indexorderby);
WRITE_NODE_FIELD(indexorderbyorig);
WRITE_ENUM_FIELD(indexorderdir, ScanDirection);
WRITE_BOOL_FIELD(indexonly);
}
static void
_outIndexOnlyScan(StringInfo str, IndexOnlyScan *node)
{
WRITE_NODE_TYPE("INDEXONLYSCAN");
_outScanInfo(str, (Scan *) node);
WRITE_OID_FIELD(indexid);
WRITE_NODE_FIELD(indexqual);
WRITE_NODE_FIELD(indexorderby);
WRITE_NODE_FIELD(indextlist);
WRITE_ENUM_FIELD(indexorderdir, ScanDirection);
}
static void
@ -1501,7 +1514,6 @@ _outIndexPath(StringInfo str, IndexPath *node)
WRITE_NODE_FIELD(indexorderbys);
WRITE_BOOL_FIELD(isjoininner);
WRITE_ENUM_FIELD(indexscandir, ScanDirection);
WRITE_BOOL_FIELD(indexonly);
WRITE_FLOAT_FIELD(indextotalcost, "%.2f");
WRITE_FLOAT_FIELD(indexselectivity, "%.4f");
WRITE_FLOAT_FIELD(rows, "%.0f");
@ -1752,8 +1764,9 @@ _outIndexOptInfo(StringInfo str, IndexOptInfo *node)
WRITE_FLOAT_FIELD(tuples, "%.0f");
WRITE_INT_FIELD(ncolumns);
WRITE_OID_FIELD(relam);
WRITE_NODE_FIELD(indexprs);
/* indexprs is redundant since we print indextlist */
WRITE_NODE_FIELD(indpred);
WRITE_NODE_FIELD(indextlist);
WRITE_BOOL_FIELD(predOK);
WRITE_BOOL_FIELD(unique);
WRITE_BOOL_FIELD(hypothetical);
@ -2707,6 +2720,9 @@ _outNode(StringInfo str, void *obj)
case T_IndexScan:
_outIndexScan(str, obj);
break;
case T_IndexOnlyScan:
_outIndexOnlyScan(str, obj);
break;
case T_BitmapIndexScan:
_outBitmapIndexScan(str, obj);
break;