[Mondrian] Cold start

Wed May 30 08:17:51 EDT 2007

Are you using aggregate tables now? To some extent, they contain your
pre-aggregated data.

A configuration I have seen work is to have live and backup Mondrian
servers with a load balancer in front of them. When new data comes into
the database:

* take the backup server offline at the load balancer level
* dump and reload the cache of the backup server with your script of MDX
commands
* put the refreshed backup server online and take the "live" server
offline
* refresh the cache of the "live" server
* put the "live" server online

Sherman

-----Original Message-----
From: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org]
On Behalf Of Pablo Sendín
Sent: Wednesday, May 30, 2007 5:10 AM
To: Mondrian developer mailing list
Subject: Re: [Mondrian] Cold start

Thanks Julian and John,

I was developing the third option, using a list of querys MDX to create
the multidimensional cube in cache. I want to obtain that Mondrian can
read the multidimensional cube and aggregated data without execute
slowly SQL querys (at least, once loaded at start). I need quick MDX
consults (about 20-30seconds) over relational database with great
amounts of data. Well, this is the reason of Mondrian cache (and I
create this cache with a script of MDX commands)

But if my server is down, the time necessary to create (another time)
Mondrian cache is excessive. My priority is to obtain the previous state
of Mondrian cache. For this, I suppose that I would have to do:

1. serialize and store in disk the Mondrian cache when all agregate data
(of multidimensional cube) are created
2. update this information when Mondrian cache change
3. recovery this data from disk when Mondrian start (if it exists,
another case Mondrian will create the cache with script of MDX commands)

Which is your opinions? Unattainable or not?

Thanks a lot,

Pablo Sendín

John Carvajal escribió:
> The script may be built from the most used querys.
>
> When a mdx is executed this is stored somewhere and later all the mdx
are
> priorized and Mondrian know which mdx can re-execute when it's start.
>
> -----Mensaje original-----
> De: mondrian-bounces at pentaho.org [mailto:mondrian-bounces at pentaho.org]
En
> nombre de Julian Hyde
> Enviado el: martes, 29 de mayo de 2007 02:19 p.m.
> Para: 'Mondrian developer mailing list'
> Asunto: RE: [Mondrian] Cold start
>
> There's no code in mondrian for cold start - just a bunch of ideas.
>
> The third option "User writes a script of MDX commands to prime the
> cache. On startup, mondrian executes this script in a background
> thread." would be the easiest to attack.
>
> Julian
>
>
>> -----Original Message-----
>> From: mondrian-bounces at pentaho.org
>> [mailto:mondrian-bounces at pentaho.org] On Behalf Of Pablo Sendín
>> Sent: Tuesday, May 29, 2007 8:35 AM
>> To: mondrian at pentaho.org
>> Subject: [Mondrian] Cold start
>>
>> Good day all,
>>
>> I am looking for procedures for cold start, ideas and designs
>> to speed
>> that up. In Mondrian roadmap I could read this option:
>>
>>> Command for mondrian to serialize cache state (definitions
>>>
>> and data)
>>
>>> to disk. When mondrian starts, read the cache state from disk
>>>
>> You know if this feature is implemented in Mondrian Project?
>> Is there
>> any API or procedure to store the Mondrian cache into the disk?
>>
>> Thanks for all,
>>
>> --
>> Pablo Sendín
>> Grupo de Tecnoloxías da Información (GTI), DET - ETSE Telecomunicación
>> pablo at enigma.det.uvigo.es
>> (+34) 986 813 407
>> (+34) 627 441 193
>>
>>
>> _______________________________________________
>> Mondrian mailing list
>> Mondrian at pentaho.org
>> http://lists.pentaho.org/mailman/listinfo/mondrian
>>
>>
>
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--
Pablo Sendín
Grupo de Tecnoloxías da Información (GTI), DET - ETSE Telecomunicación
pablo at enigma.det.uvigo.es
(+34) 986 813 407
(+34) 627 441 193

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