Re[2]: [Exim] exim's databases and sql

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Autor: Avleen Vig
Data:  
Para: exim-users
Asunto: Re[2]: [Exim] exim's databases and sql
On Mon, 6 Oct 2003 08:54:27 +0100 (BST) Philip Hazel <ph10@???> wrote:

> On Sun, 5 Oct 2003, Avleen Vig wrote:


> > You really neem to do tests, where you need to *write* a lot to the
> > database, to see how the locking effects performance. Reading for the
> > database can happen concurrently but for fallbacks, or other servers
> > which queue mail, locking to write will cause a delay.


> Indeed.


no question here. different databases will behave differently on this. i
don't know how MySQL does locking for writes; PostgreSQL uses MVCC and
writes cannot block reads. M$ SQL Server uses a nasty little promotable
row locking scheme that can cause major problems if the number of rows
affected by a write exceed a certain threshold.

richard
--
Richard Welty                                         rwelty@???
Averill Park Networking                                         518-573-7592
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