| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Florian Pflug <fgp(at)phlo(dot)org> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: why do we need two snapshots per query? |
| Date: | 2011-11-14 02:40:49 |
| Message-ID: | CA+TgmoaJ=no7NXS3qWGGL_X3kwFW_L=fbtaDaBcVEnwC_iyThA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Sun, Nov 13, 2011 at 8:57 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> In the -M extended case, we take a snapshot from exec_parse_message(),
> and the same two in the exec_bind_message() call that are taken in the
> -M prepared case. So reducing the prepared case from two snapshots to
> one will reduce the extended case from three snapshots to two, thus
> saving one snapshot per query regardless of how it's executed.
And here are the revised patches. Apply refactor-portal-start
(unchanged) first and then just-one-snapshot-v2.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| Attachment | Content-Type | Size |
|---|---|---|
| just-one-snapshot-v2.patch | application/octet-stream | 3.0 KB |
| refactor-portal-start.patch | application/octet-stream | 4.1 KB |
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