| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Andreas Karlsson <andreas(at)proxel(dot)se>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Jakob Egger <jakob(at)eggerapps(dot)at>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Refactor pg_dump as a library? |
| Date: | 2016-04-15 18:41:35 |
| Message-ID: | CA+TgmoZ9RgO-oqsx83sX3outBrwH3q=sjKDQb6EcqbMiSPVtkA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Apr 14, 2016 at 1:01 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2016-04-14 13:16:20 +0200, Andreas Karlsson wrote:
>> I am personally not a fan of the pg_get_Xdef() functions due to their heavy
>> reliance on the syscache which feels rather unsafe in combination with
>> concurrent DDL.
>
> I'm not sure I find that convincing: The state portrayed by the syscache
> is th state COPY/SELECT et al will be using. I think the angle to
> attack this is rather to allow blocking 'globally visible' DDL
> efficiently and correctly, rather than the hack pg_dump is using right now.
Maybe. I think that idea of changing the pg_get_Xdef() stuff to use
the transaction snapshot rather than the latest snapshot might be
worth considering, too.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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