| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: MVCC catalog access |
| Date: | 2013-06-03 18:57:12 |
| Message-ID: | CA+TgmoYpgCM1LUqh7n_dC_6q03at_Z2jGcLL9eKV8wYsxtq+6A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, May 30, 2013 at 1:39 AM, Michael Paquier
<michael(dot)paquier(at)gmail(dot)com> wrote:
> +1.
Here's a more serious patch for MVCC catalog access. This one
involves more data copying than the last one, I think, because the
previous version did not register the snapshots it took, which I think
is not safe. So this needs to be re-tested for performance, which I
have so far made no attempt to do.
It strikes me as rather unfortunate that the snapshot interface is
designed in such a way as to require so much data copying. It seems
we always take a snapshot by copying from PGXACT/PGPROC into
CurrentSnapshotData or SecondarySnapshotData, and then copying data a
second time from there to someplace more permanent. It would be nice
to avoid that, at least in common cases.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| Attachment | Content-Type | Size |
|---|---|---|
| mvcc-catalog-access-v3.patch | application/octet-stream | 91.9 KB |
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