| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Stephen Frost <sfrost(at)snowman(dot)net>, Peter van Hardenberg <pvh(at)pvh(dot)ca>, Peter Geoghegan <peter(dot)geoghegan86(at)gmail(dot)com>, "pgsql-hackers(at)postgresql(dot)org Hackers" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Prepared statements fail after schema changes with surprising error |
| Date: | 2013-01-23 15:14:51 |
| Message-ID: | CA+Tgmoa8wqNcMsyYj69oK6oHa-q3tTcFwPc+VbQwdyRFCTMMjw@mail.gmail.com |
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On Wed, Jan 23, 2013 at 8:10 AM, Dimitri Fontaine
<dimitri(at)2ndquadrant(dot)fr> wrote:
> Really, live DDL is not that frequent, and when you do that, you want
> transparent replanning. I can't see any use case where it's important to
> be able to run DDL in a live application yet continue to operate with
> the old (and in cases wrong) plans.
I agree with that, but I think Tom's concern is more with the cost of
too-frequent re-planning. The most obvious case in which DDL might be
frequent enough to cause an issue here is if there is heavy use of
temporary objects - sessions might be rapidly creating and dropping
objects in their own schemas. It would be unfortunate if that forced
continual replanning of queries in other sessions. I think there
could be other cases where this is an issue as well, but the
temp-object case is probably the one that's most likely to matter in
practice.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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