[
https://issues.apache.org/jira/browse/LUCENE-2362?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12853111#action_12853111
]
Michael McCandless commented on LUCENE-2362:
--------------------------------------------
I think in general Lucene should do a better job managing whether the filter is
cheap or expensive, random access or not (LUCENE-1536), and tune the
matching/scoring appropriately.
But one issue with this patch: how is scoring done? It looks like in first
pass you gather bit set, then you filter it w/ batch filter, then you iterate
again in 2nd pass to collect the docs. But that 2nd pass won't in general have
enough info to do scoring?
> Add support for slow filters with batch processing
> --------------------------------------------------
>
> Key: LUCENE-2362
> URL: https://issues.apache.org/jira/browse/LUCENE-2362
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Search
> Affects Versions: 3.0.1
> Reporter: Sergey Vladimirov
> Attachments: BatchFilter.java, IndexSearcherImpl.java
>
>
> Internal implementation of IndexSearch assumes that Filter and scorer has
> almost equal perfomance. But in our environment we have Filter implementation
> that is very expensive (in compare to scorer).
> if we have, let's say, 2k of termdocs selected by scorer (each ~250 docs) and
> 2k selected by filter, then 250k docs will be fastly checked (and filtered
> out) by scorer, and 250k docs will be slowly checked by our filter.
> Using straigthforward implementation makes search out of 60 seconds per query
> boundary, because each next() or advance() requires N queries to database PER
> CHECKED DOC. Using read ahead technique allows us to optimze it to 35 seconds
> per query. Still too slow.
> The solution to problem is firstly select all documents by scorer and filter
> them in batch by our filter. Example of implementation (with BitSet) in
> attachement. Currently it takes only ~300 millseconds per query.
--
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: [email protected]
For additional commands, e-mail: [email protected]
