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From Sorin Manolache <sor...@gmail.com>
Subject Re: Prepared Statement - cache duration (CQL3 - Cassandra 1.2.4)
Date Sun, 21 Apr 2013 10:51:20 GMT
On 2013-04-19 13:57, Stuart Broad wrote:
> Hi,
>
> I am using Cassandra.Client
> prepare_cql3_query/execute_prepared_cql3_query to create and run some
> prepared statements.  It is working well but I am unclear as to how long
> the server side 'caches' the prepared statements.  Should a prepared
> statement be prepared for every new Cassandra.Client?  Based on my
> limited testing it seems like I can create some prepared statements in
> one Cassandra.Client and use in another but I am not sure how
> reliable/lasting this is i.e.  If I called the prepared statement again
> the next day would it still exist?  What about if cassandra was re-started?
>
> _Background:_
> I am creating prepared statements for batch updates of pre-defined
> lengths (e.g. 10000, 1000, 500, 250, 50, 10, 1) and wanted to know if
> these could just be set up once.  We felt that using the prepared
> statements was easier than escaping values within a CQL statement and
> probably more performant.
>
> Thanks in advance for your help.
>

I've looked in Cassandra's code (v1.2.3). The cache of prepared 
statements has a size of 100,000. So if you prepare more than 100 
thousand statements, the least recently used ones will vanish. You'll 
get the exception PreparedQueryNotFoundException, code 0x2500.

Regards,
Sorin



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