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From "Nick Bailey (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4396) Subcolumns not removed when compacting tombstoned super column
Date Fri, 29 Jun 2012 21:44:43 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13404238#comment-13404238
] 

Nick Bailey commented on CASSANDRA-4396:
----------------------------------------

This is also a problem with simply flushing super column deletes:

>From a fresh cluster I can create a supercolumn with subcolumns, delete that supercolumn,
trigger a flush with nodetool, and observer the subcolumn data in the flushed sstable with
sstable2json.
                
> Subcolumns not removed when compacting tombstoned super column
> --------------------------------------------------------------
>
>                 Key: CASSANDRA-4396
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4396
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 1.0.0
>            Reporter: Nick Bailey
>            Assignee: Jonathan Ellis
>             Fix For: 1.0.11, 1.1.3
>
>
> When we compact a tombstone for a super column with the old data for that super column,
we end up writing the deleted super column and all the subcolumn data that is now worthless
to the new sstable. This is especially inefficient when reads need to scan tombstones during
a slice.
> Here is the output of a simple test I ran to confirm:
> insert supercolumn, then flush
> {noformat}
> Nicks-MacBook-Pro:12:20:52 cassandra-1.0] cassandra$ bin/sstable2json ~/.ccm/1node/node1/data/Keyspace2/Super4-hd-1-Data.db

> {
> "6b657931": {"supercol1": {"deletedAt": -9223372036854775808, "subColumns": [["737562636f6c31","7468697320697320612074657374",1340990212532000]]}}
> }
> {noformat}
> delete supercolumn, flush again
> {noformat}
> [Nicks-MacBook-Pro:12:20:59 cassandra-1.0] cassandra$ bin/nodetool -h localhost flush
> [Nicks-MacBook-Pro:12:22:41 cassandra-1.0] cassandra$ bin/sstable2json ~/.ccm/1node/node1/data/Keyspace2/Super4-hd-2-Data.db

> {
> "6b657931": {"supercol1": {"deletedAt": 1340990544005000, "subColumns": []}}
> }
> {noformat}
> compact and check resulting sstable
> {noformat}
> [Nicks-MacBook-Pro:12:22:55 cassandra-1.0] cassandra$ bin/nodetool -h localhost compact

> [Nicks-MacBook-Pro:12:23:09 cassandra-1.0] cassandra$ bin/sstable2json ~/.ccm/1node/node1/data/Keyspace2/Super4-hd-3-Data.db

> {
> "6b657931": {"supercol1": {"deletedAt": 1340990544005000, "subColumns": [["737562636f6c31","7468697320697320612074657374",1340990212532000]]}}
> }
> [Nicks-MacBook-Pro:12:23:20 cassandra-1.0] cassandra$ 
> {noformat}

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