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From Lance Norskog <goks...@gmail.com>
Subject Re: OOM on sorting on dynamic fields
Date Sat, 19 Jun 2010 00:28:27 GMT
The Lucene implementation of sorting creates an array of four-byte
ints for every document in the index, and another array of the unique
values in the field.
If the timestamps are 'date' or 'tdate' in the schema, they do not
need the second array.

You can also sort by a field's with a function query. This does not
build the arrays, but might be a little slower.
Yes, the sort arrays (and also facet values for a field) should be
controlled by a fixed-size cache, but they are not.

On Fri, Jun 18, 2010 at 7:52 AM, Matteo Fiandesio
<matteo.fiandesio@gmail.com> wrote:
> Hello,
> we are experiencing OOM exceptions in our single core solr instance
> (on a (huge) amazon EC2 machine).
> We investigated a lot in the mailing list and through jmap/jhat dump
> analyzing and the problem resides in the lucene FieldCache that fills
> the heap and blows up the server.
>
> Our index is quite small but we have a lot of sort queries  on fields
> that are dynamic,of type long representing timestamps and are not
> present in all the documents.
> Those queries apply sorting on 12-15 of those fields.
>
> We are using solr 1.4 in production and the dump shows a lot of
> Integer/Character and Byte Array filled up with 0s.
> With solr's trunk code things does not change.
>
> In the mailing list we saw a lot of messages related to this issues:
> we tried truncating the dates to day precision,using missingSortLast =
> true,changing the field type from slong to long,setting autowarming to
> different values,disabling and enabling caches with different values
> but we did not manage to solve the problem.
>
> We were thinking to implement an LRUFieldCache field type to manage
> the FieldCache as an LRU and preventing but, before starting a new
> development, we want to be sure that we are not doing anything wrong
> in the solr configuration or in the index generation.
>
> Any help would be appreciated.
> Regards,
> Matteo
>



-- 
Lance Norskog
goksron@gmail.com

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