Fujii.Yuki@df.MitsubishiElectric.co.jp писал 2023-09-28 07:40:
>> I'm not sure that I like this mechanics of adding sort group clauses -
>> it seems we do in core additional work, which is of use only for
>> one extension, but at least it seems to be working.
> We cannot deparse the original sort group clauses and pathtarget
> when performing partial aggreggate pushdown by any FDWs.
> So I think the additional sort group clauses and pathtarget are
> needed by any FDWs, not only postgres_fdw.
>
Hi.
It seems to me that *fdw postfixes don't clarify things, but just make
naming more ugly.
+ * Adding these Vars and PlaceHolderVars to PathTarget,
+ * FDW cannot deparse this by the original List of SortGroupClauses.
+ * So, before this adding process,
+ * setGroupClausePartial generates another Pathtarget and another
+ * List of SortGroupClauses for FDW.
It seems that something like:
/*
* Modified PathTarget cannot be used by FDW as-is to deparse this
statement.
* So, before modifying PathTarget, setGroupClausePartial generates
* another Pathtarget and another list List of SortGroupClauses
* to make deparsing possible.
*/
sounds better.
--
Best regards,
Alexander Pyhalov,
Postgres Professional