[Mondrian] Mondrian and pgpool

John Carvajal jcarvajal at parquesoft.com
Tue Aug 17 21:17:03 EDT 2010


ok, will try to run with the debug turned on according to your suggestion.

our idea is to store the most frequently executed MDX and (if the data have
not changed) re-run but with the cache in the database, this would be a
scenario in which the query cache in the database is useful, because the
mondrian cache is active while the application server is active, but if
something happens, the entire cache is lost and this can be a big problem if
it happens in full working day.


the other possible scenario is to store the SQL to run and refill the cache
within the same ETL processes to populate the data warehouse, then will be
applied for user queries by mondrian performance should not be a problem


In these two scenarios, maybe there are opportunities to improve the times
without changing the Mondrian architecture.

 

De: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org] En
nombre de Julian Hyde
Enviado el: martes, 17 de agosto de 2010 03:12 p.m.
Para: 'Mondrian developer mailing list'
Asunto: RE: [Mondrian] Mondrian and pgpool

 

Mondrian sends all queries using mondrian.rolap.RolapUtil.executeQuery. This
creates a mondrian.rolap.SqlStatement, then calls SqlStatement.execute. As
you can see, it gets a connection from the data source (which is probably a
connection pool), calls either Connection.createStatement() or
Connection.createStatement(int, int), then calls
Statement.executeQuery(String). None of this is particularly unusual, except
perhaps the (int, int) version of createStatement.

 

I don't think you'll get much advantage from query result caching. Mondrian
caches the results of queries, and as a result doesn't tend to issue the
same query twice.

 

Query parallelization may be useful.

 

I can't help you any further than this. I would suggest running mondrian in
a debugger so that you can see the lifecycle and also look at field values
in pgpool connections and statements.

 

Julian

 


  _____  


From: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org] On
Behalf Of John Carvajal
Sent: Tuesday, August 10, 2010 11:32 PM
To: 'Mondrian developer mailing list'
Subject: RE: [Mondrian] Mondrian and pgpool

Any idea ?

 

De: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org] En
nombre de John Carvajal
Enviado el: viernes, 23 de julio de 2010 07:27 a.m.
Para: mondrian at pentaho.org
Asunto: [Mondrian] Mondrian and pgpool

 

I've been working on an idea, our idea is to work with pgpool-II to improve
the performance of some data access, basically what we need is to use the
query_cache and the option to parallelize the querys. 

The idea sounds interesting to us because we may take full advantage of the
current ROLAP and management about how to access the data.

we install the pgpool and works well (there is a bug in the query_cache
already correct with the help of a post), then we test from the interface
and makes the cache without difficulty, but when I tried to work with
Mondrian query_cache simply does not work.

The theory that I have (supported some debug to pgpool) is when mondrian
send the SQL statement, it would seem that is sent in a special way, maybe
this comes in a transaction or an execute, but it makes the pgpool
identified as a different query and process it differently and do not save
the cache.

if anyone has any idea about it or can guide us to see if we can configure
the JDBC driver in some way to stop this from happening or if we need to do
some additional configuration, please let us know.

Thanks 

 

 

John Carvajal Arciniegas

Gerente Innovacion y Desarrollo

Grupo Empresarial BIT

PBX: (57 2) 485 46 61 

jcarvajal at grupobit.net <mailto:aecheverry at grupobit.net> 

www.grupobit.net

 

 

 

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