hbase-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Joe Pallas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-3484) Replace memstore's ConcurrentSkipListMap with our own implementation
Date Tue, 26 Apr 2011 21:59:03 GMT

    [ https://issues.apache.org/jira/browse/HBASE-3484?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13025463#comment-13025463
] 

Joe Pallas commented on HBASE-3484:
-----------------------------------

This issue was cited by jdcryans as related to unfortunate performance seen in the following
case:

A test program fills a single row of a family with tens of thousands of sequentially increasing
qualifiers.  Then it performs random gets (or exists) of those qualifiers.  The response time
seen is (on average) proportional to the ordinal position of the qualifier.  If the table
is flushed before the random tests begin, then the average response time is basically constant,
independent of the qualifier's ordinal position.

I'm not sure that either of the two points in the description actually covers this case, but
I don't know enough to say.


> Replace memstore's ConcurrentSkipListMap with our own implementation
> --------------------------------------------------------------------
>
>                 Key: HBASE-3484
>                 URL: https://issues.apache.org/jira/browse/HBASE-3484
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.92.0
>            Reporter: Todd Lipcon
>            Assignee: Todd Lipcon
>             Fix For: 0.92.0
>
>
> By copy-pasting ConcurrentSkipListMap into HBase we can make two improvements to it for
our use case in MemStore:
> - add an iterator.replace() method which should allow us to do upsert much more cheaply
> - implement a Set directly without having to do Map<KeyValue,KeyValue> to save
one reference per entry
> It turns out CSLM is in public domain from its development as part of JSR 166, so we
should be OK with licenses.

--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message