On 2016/01/21 7:04, Alvaro Herrera wrote:
Etsuro Fujita wrote:
On second thought, I noticed that detecting whether we see a system column
that way needs more cycles in cases where the reltargetlist and the
restriction clauses don't contain any system columns. ISTM that such cases
are rather common, so I'm inclined to keep that code as-is.
Ah, I see now what you did there. I was thinking you'd have the
foreach(restrictinfo) loop, then once the loop is complete scan the
bitmapset; not scan the bitmap set scan inside the other loop.
Ah, I got to the point. I think that is a good idea. The additional
cycles for the worst case are bounded and negligible. Please find
attached an updated patch.
Best regards,
Etsuro Fujita
*** a/src/backend/optimizer/plan/createplan.c
--- b/src/backend/optimizer/plan/createplan.c
***************
*** 2099,2108 **** create_foreignscan_plan(PlannerInfo *root, ForeignPath *best_path,
RelOptInfo *rel = best_path->path.parent;
Index scan_relid = rel->relid;
Oid rel_oid = InvalidOid;
- Bitmapset *attrs_used = NULL;
Plan *outer_plan = NULL;
- ListCell *lc;
- int i;
Assert(rel->fdwroutine != NULL);
--- 2099,2105 ----
***************
*** 2171,2206 **** create_foreignscan_plan(PlannerInfo *root, ForeignPath *best_path,
}
/*
! * Detect whether any system columns are requested from rel. This is a
! * bit of a kluge and might go away someday, so we intentionally leave it
! * out of the API presented to FDWs.
! *
! * First, examine all the attributes needed for joins or final output.
! * Note: we must look at reltargetlist, not the attr_needed data, because
! * attr_needed isn't computed for inheritance child rels.
*/
! pull_varattnos((Node *) rel->reltargetlist, rel->relid, &attrs_used);
!
! /* Add all the attributes used by restriction clauses. */
! foreach(lc, rel->baserestrictinfo)
{
! RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
! pull_varattnos((Node *) rinfo->clause, rel->relid, &attrs_used);
! }
! /* Now, are any system columns requested from rel? */
! scan_plan->fsSystemCol = false;
! for (i = FirstLowInvalidHeapAttributeNumber + 1; i < 0; i++)
! {
! if (bms_is_member(i - FirstLowInvalidHeapAttributeNumber, attrs_used))
{
! scan_plan->fsSystemCol = true;
! break;
}
- }
! bms_free(attrs_used);
return scan_plan;
}
--- 2168,2228 ----
}
/*
! * If rel is a base relation, detect whether any system columns are
! * requested from the rel. (If rel is a join relation, rel->relid will be
! * 0, but there can be no Var with relid 0 in the reltargetlist or the
! * restriction clauses, so we skip this in that case. Note that any such
! * columns in base relations that were joined are assumed to be contained
! * in fdw_scan_tlist.) This is a bit of a kluge and might go away someday,
! * so we intentionally leave it out of the API presented to FDWs.
*/
! scan_plan->fsSystemCol = false;
! if (scan_relid > 0)
{
! Bitmapset *attrs_used = NULL;
! ListCell *lc;
! int i;
! /*
! * First, examine all the attributes needed for joins or final output.
! * Note: we must look at reltargetlist, not the attr_needed data,
! * because attr_needed isn't computed for inheritance child rels.
! */
! pull_varattnos((Node *) rel->reltargetlist, scan_relid, &attrs_used);
! /* Now, are any system columns requested from rel? */
! for (i = FirstLowInvalidHeapAttributeNumber + 1; i < 0; i++)
{
! if (bms_is_member(i - FirstLowInvalidHeapAttributeNumber, attrs_used))
! {
! scan_plan->fsSystemCol = true;
! break;
! }
}
! /* Examine all the attributes used by restriction clauses, if needed */
! if (!scan_plan->fsSystemCol)
! {
! foreach(lc, rel->baserestrictinfo)
! {
! RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
!
! pull_varattnos((Node *) rinfo->clause, scan_relid, &attrs_used);
! }
!
! /* Now, are any system columns requested from rel? */
! for (i = FirstLowInvalidHeapAttributeNumber + 1; i < 0; i++)
! {
! if (bms_is_member(i - FirstLowInvalidHeapAttributeNumber, attrs_used))
! {
! scan_plan->fsSystemCol = true;
! break;
! }
! }
! }
!
! bms_free(attrs_used);
! }
return scan_plan;
}
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