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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-2872) While dropping and recreating an index, incremental snapshotting can hang
Date Tue, 19 Jul 2011 16:54:58 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-2872?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13067838#comment-13067838
] 

Sylvain Lebresne commented on CASSANDRA-2872:
---------------------------------------------

bq. That's why I prefer the scan approach

Yeah, I kind of wrote my comment before as things were coming to me, in particular I wrote
that I was preferring the second solution before realizing we would still need to scan. Agreeing
that the scan approach is cleaner/easier.

On the patch, shouldn't we only include the sstables for the column family we're creating.
I know it's ok to take the max for all cfs, but it feels a bit random unless we have only
one global generation. And could be worst avoiding 2-3 mails on the mailing of people wondering
why that has changed (I mean, I'm sure someone will remark it) :). 

> While dropping and recreating an index, incremental snapshotting can hang 
> --------------------------------------------------------------------------
>
>                 Key: CASSANDRA-2872
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2872
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 0.7.4
>            Reporter: Sylvain Lebresne
>            Assignee: Jonathan Ellis
>            Priority: Minor
>             Fix For: 0.7.8, 0.8.2
>
>         Attachments: 2872.txt
>
>
> When creating a hard link (at list with JNA), link() hang if the target of the
> link already exists. In theory though, we should not hit that situation
> because we use a new directory for each manual snapshot and the generation
> number of the sstables should prevent this from hapenning with increment
> snapshot.
> However, when you drop, then recreate a secondary index, if the sstables are
> deleted after the drop and before we recreate the index, the recreated index
> sstables will start with a generation to 0. Thus, when we start backuping them
> incrementally, it will conflict with the sstables of the previously dropped
> index.
> First, we should check for the target existance because calling link() to at
> least avoid hanging. But then we must make sure that when we drop, then
> recreate an index, we will either not name the sstables the same way or the
> incremental snapshot use a different directory.

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