| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: MVCC catalog access |
| Date: | 2013-05-23 03:05:40 |
| Message-ID: | CA+TgmoYu6qpr+5SVqCDNW+6i4M-w4RtCQKPBaDGcr9Kmcjz52A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, May 22, 2013 at 11:02 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> On 2013-05-22 22:51:13 -0400, Robert Haas wrote:
>> In discussions today, Tom Lane suggested testing the time to start up
>> a backend and run a simple query such as "SELECT 2+2" in the absence
>> of a relcache file.
>
>> I did this and can't measure any overhead as a result of MVCC catalog
>> access. I tried it with no active connections. I tried it with 600
>> idle active connections (to make taking MVCC snapshots more
>> expensive).
>
> Did you try it with the 600 transactions actually being in a transaction
> and having acquired a snapshot?
No... I can hack something up for that.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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