lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] Closed: (LUCENE-983) Enable IndexReader to merge tail segments on demand, in RAM, when opening
Date Fri, 17 Aug 2007 21:36:30 GMT

     [ https://issues.apache.org/jira/browse/LUCENE-983?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Michael McCandless closed LUCENE-983.
-------------------------------------

    Resolution: Won't Fix

On further discussion in LUCENE-845 it doesn't look like this idea is worth pursuing...

> Enable IndexReader to merge tail segments on demand, in RAM, when opening
> -------------------------------------------------------------------------
>
>                 Key: LUCENE-983
>                 URL: https://issues.apache.org/jira/browse/LUCENE-983
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Michael McCandless
>            Assignee: Michael McCandless
>            Priority: Minor
>             Fix For: 2.3
>
>
> Spinoff from LUCENE-845.
> In LUCENE-845, the IndexWriter must pay a high cost (O(N^2) merge
> cost) for keeping the number of segments "always small" in the case
> where flushes of very small segments (1 doc as worst case) happen
> frequently.  This happens in "low latency" applications.
> This is because IndexWriter must be ready "at every moment" for an
> IndexReader to open the index.
> But, if we allow IndexReader to use some RAM (give it a RAM buffer) to
> load the long tail of small segments into a RAMDirectory, and then
> merge them (in RAM), this allows IndexReader to still have good
> performance on the index without IndexWriter paying this high merge
> cost.  This effectively allows us to optimize the tail segments "on
> demand" when a reader needs to use them.
> When we combine this with LUCENE-743 (efficient "re-open" of a reader)
> then we should be able to efficiently handle low latency applications.

-- 
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