[Kamailio-Users] [offtopic] update vs delete/insert

[Daniel-Constantin Mierla]

Hello,

On 10/06/08 12:12, Henning Westerholt wrote:
> On Monday 06 October 2008, toly wrote:
>   
>> I can answer about Sybase: update is delete/insert, and optimizer will do
>> it more effectively the executing 2 different transaction.
>>     
>
> Hi Daniel,
>
> i think that doing a update is faster then doing two queries. The core need to 
> construct another SQL string, the DB need to be parse this and so on.. It 
> probably depend on the DB type, and exact configuration, but i doubt the 
> difference will be that relevant. Doing a delete and insert in two steps is 
> also different from the update that you have one small interval of 
> inconsisteny where the old record has been deleted, and the new one not yet 
> created (if you don't use transactions).
>
> Aparently also for postgres an UPDATE is also the same as and DELETE/INSERT.
> [1], which means its faster here too.
>   
ok. I was looking to use prepare statements or a stored procedure. 
However, seems some db servers are doing it in this way, so probably 
there are internal optimizations.

Thanks,
Daniel

> Cheers,
>
> Henning
>
>
> [1] http://archives.postgresql.org/pgsql-performance/2005-12/msg00589.php
>
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-- 
Daniel-Constantin Mierla
http://www.asipto.com