lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Toke Eskildsen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-2335) optimization: when sorting by field, if index has one segment and field values are not needed, do not load String[] into field cache
Date Fri, 19 Mar 2010 23:36:27 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12847650#action_12847650
] 

Toke Eskildsen commented on LUCENE-2335:
----------------------------------------

I obviously have a share in this and would like to give the inner workings a go (I've made
a proof of concept at http://github.com/tokee/lucene that I'll use as base). However, I am
not all that familiar with the finer details of the Lucene code base, so I'll proably need
help for integrating the code.

If I read the Lucene code correctly, the actual Strings need only be resolved for the requested
X documents (using FieldComparator.value). If this is true, there is no need for stored fields:
We can get the Strings from the indexed fields instead, as we keep track of the ordinals for
the Terms.

> optimization: when sorting by field, if index has one segment and field values are not
needed, do not load String[] into field cache
> ------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: LUCENE-2335
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2335
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Search
>            Reporter: Michael McCandless
>            Priority: Minor
>             Fix For: 3.1
>
>
> Spinoff from java-dev thread "Sorting with little memory: A suggestion", started by Toke
Eskildsen.
> When sorting by SortField.STRING we currently ask FieldCache for a StringIndex on that
field.
> This can consumes tons of RAM, when the values are mostly unique (eg a title field),
as it populates both int[] ords as well as String[] values.
> But, if the index is only one segment, and the search sets fillFields=false, we don't
need the String[] values, just the int[] ords.  If the app needs to show the fields it can
pull them (for the 1 page) from stored fields.
> This can be a potent optimization -- alot of RAM saved -- for optimized indexes.
> When fixing this we must take care to share the int[] ords if some queries do fillFields=true
and some =false... ie, FieldCache will be called twice and it should share the int[] ords
across those invocations.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


---------------------------------------------------------------------
To unsubscribe, e-mail: java-dev-unsubscribe@lucene.apache.org
For additional commands, e-mail: java-dev-help@lucene.apache.org


Mime
View raw message