| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Boszormenyi Zoltan <zb(at)cybertec(dot)at> |
| Cc: | Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Synchronization levels in SR |
| Date: | 2010-09-06 21:02:13 |
| Message-ID: | 1283806933.1834.10557.camel@ebony |
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| Lists: | pgsql-hackers |
On Mon, 2010-09-06 at 22:32 +0200, Boszormenyi Zoltan wrote:
> (in commit)
> write wal record
> release locks/etc <xact2 can proceed from here
> wait for sync ack
>
> In the first case, the contention is obviously increased.
> With this, we are creating more idle time in the server
> instead of letting other transactions do their jobs as soon
> as possible. The second method was implemented in my
> patch. Are there any drawbacks with this?
Then I respectfully suggest that you're releasing locks too early.
Your proposal would allow a 2nd user to see the results of the 1st
user's transaction before the 1st user knew about whether it had
committed or not.
I know why you want that, but I don't think its right.
This has very little, if anything, to do with mixing async/sync
connections. You make it sound like all transactions always wait for
other transactions, which they definitely don't, especially in
reasonably well designed applications.
--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Training and Services
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