Re: IMPORT FOREIGN SCHEMA return create foreign table commands are those further filtered in LIMIT and EXCEPT cases? - Mailing list pgsql-hackers

From Paragon Corporation
Subject Re: IMPORT FOREIGN SCHEMA return create foreign table commands are those further filtered in LIMIT and EXCEPT cases?
Date
Msg-id 000a01d14414$eb3c3040$c1b490c0$@pcorp.us
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In response to Re: IMPORT FOREIGN SCHEMA return create foreign table commands are those further filtered in LIMIT and EXCEPT cases?  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: IMPORT FOREIGN SCHEMA return create foreign table commands are those further filtered in LIMIT and EXCEPT cases?  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
"Paragon Corporation" <lr@pcorp.us> writes:
>> So I am guessing you guys are filtering the list so that it works for 
>> all FDWs even if the FDW author doesn't directly handle LIMIT / EXCEPT
clause?

> Yes.  The FDW author is not expected to implement those clauses; where do
you see documentation saying otherwise?
        > regards, tom lane

I didn't. I was copying the postgres_fdw and noticed it implemented them
directly.

Is there an issue with handling it ahead of time?  In the case of ogr_fdw,
there is an extra call after getting list of tables to get the data
structure for a specific table,
So I thought implementing it directly would save some cycles, especially
since some data sources require inspection of the data to infer the
structure so could be very expensive.


Thanks,
Regina







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