Horton

Re: pgsql_fdw, FDW for PostgreSQL server

Shigeru Hanada <shigeru.hanada@gmail.com>

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From: Shigeru Hanada <shigeru.hanada@gmail.com>
To: Albe Laurenz <laurenz.albe@wien.gv.at>
Cc: Tom Lane *EXTERN* <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Kohei KaiGai <kaigai@kaigai.gr.jp>, Hitoshi Harada <umi.tanuki@gmail.com>, Martijn van Oosterhout <kleptog@svana.org>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2011-12-13T12:22:24Z
Lists: pgsql-hackers 
(2011/12/13 18:57), Albe Laurenz wrote:
> Maybe I'm missing something, but if pushdown worked as follows:
> 
> - Push down only system functions and operators on system types.
> - Only push down what is guaranteed to work.

Oh, I didn't care whether system data types.  Indeed user defined types
would not be safe to push down.

> then the only things we would miss out on are encoding- or
> collation-sensitive string operations.
> 
> Is that loss so big that it warrants a lot of effort?

It depends on the definition of "collation-sensitive".  If we define it
as "all operations which might handle any collation-sensitive element",
all functions/operators which take any of character data types (text,
varchar, bpchar, sql_identifier, etc.) are unable to be pushed down.

Regards,
-- 
Shigeru Hanada