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From "Jeff Jirsa (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-13496) table with lots of column ( tens of thousands columns), system is very slow
Date Tue, 16 May 2017 15:53:04 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-13496?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16012627#comment-16012627
] 

Jeff Jirsa edited comment on CASSANDRA-13496 at 5/16/17 3:52 PM:
-----------------------------------------------------------------

The debug messages are just debug messages, not indicative of a problem. Can you quantify
"very slow"? 

In general, a table with tens of thousands of columns of any kind sounds like an awful data
model, and it would benefit you greatly to redesign it.  Looking at your schema, it's actually
thousands of lists, which is even worse. 

This is a horribly broken data model, and incredibly unlikely to work well in cassandra at
any time in the next 2-3 years. 


was (Author: jjirsa):
The debug messages are just debug messages, not indicative of a problem. Can you quantify
"very slow"? 

In general, a table with tens of thousands of columns sounds like an awful data model, and
it would benefit you greatly to redesign it. 

> table with lots of column ( tens of thousands columns), system is very slow 
> ----------------------------------------------------------------------------
>
>                 Key: CASSANDRA-13496
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13496
>             Project: Cassandra
>          Issue Type: Bug
>          Components: CQL
>         Environment: linux redhat 6.5 cassandra 3.10 using 2i
> cpu : 4 core , memory: 16G  . 5 servers
> using gocql client
>            Reporter: lizg
>            Priority: Minor
>              Labels: usability
>         Attachments: debug.log, sql.txt
>
>
> In debug.log there are lots of 
> DEBUG [COMMIT-LOG-ALLOCATOR] 2017-05-04 08:54:35,769 AbstractCommitLogSegmentManager.java:107
- No segments in reserve; creating a fresh one
> DEBUG [MemtablePostFlush:54] 2017-05-04 08:49:19,699 AbstractCommitLogSegmentManager.java:329
- Segment CommitLogSegment(/home/matrix/cassandra/commitlog/CommitLog-6-1493809341337.log)
is no longer active and will be deleted now



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