[
https://issues.apache.org/jira/browse/LUCENE-2694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12934260#action_12934260
]
Michael McCandless commented on LUCENE-2694:
--------------------------------------------
BTW, one use case where this patch should show a sizable performance gain is a
"primary key lookup" against a multi-segment index.
So this'd be a TermQuery against eg an "id" field, where the app knows at most
one doc contains the requested value.
Today, we pay a high price for the 2nd pass, because we do not cache a miss
against a segment. So on the first pass (computing IDF) we know which segment
has a match and which segments do not, but then on the 2nd pass we re-pay the
lookup cost against all the misses (the single segment w/ the hit will be
cached).
So this ought to be a big win... especially once we combine this w/ the
speedups from pulsing codec (we still need to cutover to this as a default)
then primary key lookups in a Lucene index will be much faster...
> MTQ rewrite + weight/scorer init should be single pass
> ------------------------------------------------------
>
> Key: LUCENE-2694
> URL: https://issues.apache.org/jira/browse/LUCENE-2694
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Search
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Fix For: 4.0
>
> Attachments: LUCENE-2694.patch, LUCENE-2694.patch
>
>
> Spinoff of LUCENE-2690 (see the hacked patch on that issue)...
> Once we fix MTQ rewrite to be per-segment, we should take it further and make
> weight/scorer init also run in the same single pass as rewrite.
--
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]
