Re: How to speed up Exclusive Locking - Mailing list pgsql-general

From Bernd Helmle
Subject Re: How to speed up Exclusive Locking
Date
Msg-id 378dea27826636cae6e28ff7ef9cce80@oopsware.de
Whole thread Raw
In response to How to speed up Exclusive Locking  (David Goodenough <david.goodenough@btconnect.com>)
Responses Re: How to speed up Exclusive Locking  (David Goodenough <david.goodenough@btconnect.com>)
List pgsql-general


On Tue, 5 Dec 2006 10:18:21 +0000, David Goodenough <david.goodenough@btconnect.com> wrote:

[...]

> The first bits of the sync are done without locking the source tables, and
> I do these until I find less than some suitable threshold of records
> needing
> to be updated.  Then I lock the source tables and do the final sync.
>
> The statements issued to lock each table is:-
>  LOCK TABLE table IN EXCLUSIVE MODE; SELECT 1 FROM table;
>

So why selecting '1' for each row after locking the relation before? I don't
know HA-JDBC but this looks really useless. Remove the SELECT and use
the LOCK TABLE command within the transaction which does the sync for you.

Bernd

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