[
https://issues.apache.org/jira/browse/LUCENE-10574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17538448#comment-17538448
]
Adrien Grand commented on LUCENE-10574:
---------------------------------------
It's not about absolute segment sizes, it's more about computing balanced
merges. Say you have N 1-document segments and want to merge them down to a
single segment, 10 segments at a time. If you always compute perfectly balanced
merges then each document participates in O(log(N)) merges so it takes O(N
log(N)) to get down to a single segment. If you take the naive approach of
always merging the biggest segment you got so far with 9 1-document segments
then each document participates in O(N) merges so it takes O(N^2) to get down
to a single segment.
As bad as the second approach sounds, this is what TieredMergePolicy does with
segments that are below the floor segment size.
> Remove O(n^2) from TieredMergePolicy or change defaults to one that doesn't
> do this
> -----------------------------------------------------------------------------------
>
> Key: LUCENE-10574
> URL: https://issues.apache.org/jira/browse/LUCENE-10574
> Project: Lucene - Core
> Issue Type: Bug
> Reporter: Robert Muir
> Priority: Major
>
> Remove {{floorSegmentBytes}} parameter, or change lucene's default to a merge
> policy that doesn't merge in an O(n^2) way.
> I have the feeling it might have to be the latter, as folks seem really wed
> to this crazy O(n^2) behavior.
--
This message was sent by Atlassian Jira
(v8.20.7#820007)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org
For additional commands, e-mail: issues-h...@lucene.apache.org
