Re: Using GROUPING SETS with more than one set disables predicate pushdown? - Mailing list pgsql-performance

From Andres Freund
Subject Re: Using GROUPING SETS with more than one set disables predicate pushdown?
Date
Msg-id 64AFD0D3-9782-4D3B-9366-5B9EEA4DCB0F@anarazel.de
Whole thread Raw
In response to Re: Using GROUPING SETS with more than one set disables predicate pushdown?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance

On November 21, 2017 6:49:26 AM PST, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>Zakhar Shapurau <zak@zvs.no> writes:
>
>Presumably, we could examine the grouping sets to identify column(s)
>present in all sets, and then allow the optimization for clauses that
>reference only such columns.  Or maybe I'm misreading the comment
>(but then it needs clarification).

By memory that sounds about right. IIRC we'd some slightly more elaborate logic when GS were introduced, but had to
takeit out as buggy, and it was too late in the development cycle to come up with something better. 

Andres

Andres
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