| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Stephen Frost <sfrost(at)snowman(dot)net> |
| Cc: | Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)jp>, Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>, Jim Mlodgenski <jimmy76(at)gmail(dot)com>, PgHacker <pgsql-hackers(at)postgresql(dot)org>, Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Subject: | Re: Custom Scan APIs (Re: Custom Plan node) |
| Date: | 2014-03-04 14:48:33 |
| Message-ID: | 6401.1393944513@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Stephen Frost <sfrost(at)snowman(dot)net> writes:
> * Ashutosh Bapat (ashutosh(dot)bapat(at)enterprisedb(dot)com) wrote:
>> During EXPLAIN, ExecInitNode() is called. If ExecInitNode() fires queries
>> to foreign servers, those would be fired while EXPLAINing a query as well.
>> We want to avoid that. Instead, we can run EXPLAIN on that query at foreign
>> server. But again, not all foreign servers would be able to EXPLAIN the
>> query e.g. file_fdw. OR totally avoid firing query during ExecInitNode(),
>> if it's for EXPLAIN (except for ANALYSE may be).
> Agreed that we wouldn't want to actually run a query when it's just
> being explain'd. If the FDW can't tell the difference then we'd need to
> address that, of course.
EXEC_FLAG_EXPLAIN_ONLY ...
regards, tom lane
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