Kohei KaiGai wrote:
> Probably, it is helpful to provide a helper function that fetches an
attribute-
> number of pseudo "rowid" column from the supplied targetlist.
> If we have GetPseudoRowidColumn() at foreign/foreign.c, the avove
> routine can be rewritten as:
>
> static AttrNumber
> fileGetForeignRelWidth(PlannerInfo *root,
> RelOptInfo *baserel,
> Relation foreignrel,
> bool inhparent, List
*targetList)
> {
> FileFdwPlanState *fdw_private;
> AttrNumber nattrs = RelationGetNumberOfAttributes(foreignrel);
> AttrNumber anum_rowid;
>
> fdw_private = palloc0(sizeof(FileFdwPlanState));
> anum_rowid = GetPseudoRowidColumn(..., targetList);
> if (anum_rowid > 0)
> {
> Assert(anum_rowid > nattrs);
> fdw_private->anum_rowid
> = makeDefElem("anum_rowid", (Node
*)makeInteger(anum_rowid));
> nattrs = anum_rowid;
> }
> baserel->fdw_private = fdw_private;
>
> return nattrs;
> }
>
> In case when FDW drive wants to push-down other target entry into
foreign-
> side, thus, it needs multiple pseudo-columns, it is decision of the
extension.
> In addition, it does not take API change in the future, if some more
additional
> pseudo-column is required by some other new features.
>
> How about your opinion?
I think that this is better than what I suggested.
Yours,
Laurenz Albe
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