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From "Jeremiah Jordan (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-9195) commitlog replay only actually replays mutation every other time
Date Thu, 23 Apr 2015 14:02:39 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-9195?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14509108#comment-14509108
] 

Jeremiah Jordan edited comment on CASSANDRA-9195 at 4/23/15 2:01 PM:
---------------------------------------------------------------------

Restoring data you truncated would just be putting back the auto snapshot sstables.  For PITR
 where the restore time is after truncate time I think the correct thing to do is is you want
to only restore the stuff from after truncate until the PITR time.  If the PITR time is before
the truncate time, then you would clear the truncate meta data before restoring.


was (Author: jjordan):
Restoring data you truncated would just be putting back the auto snapshot sstables.  For PITR
 where the restore time is after truncate time I think the correct thing to do is is you want
to only restore the stuff from after truncate until the PITR time.  If the PITR time is before
the truncate time, then you would clear the truncate data before restoring.

> commitlog replay only actually replays mutation every other time
> ----------------------------------------------------------------
>
>                 Key: CASSANDRA-9195
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9195
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Jon Moses
>            Assignee: Branimir Lambov
>            Priority: Critical
>             Fix For: 2.1.5
>
>         Attachments: loader.py
>
>
> Version: Cassandra 2.1.4.374 | DSE 4.7.0
> The main issue here is that the restore-cycle only replays the mutations
> every other try.  On the first try, it will restore the snapshot as expected
> and the cassandra system load will show that it's reading the mutations, but
> they do not actually get replayed, and at the end you're left with only the
> snapshot data (2k records).
> If you re-run the restore-cycle again, the commitlogs are replayed as expected,
> and the data expected is present in the table (4k records, with a spot check of 
> record 4500, as it's in the commitlog but not the snapshot).
> Then if you run the cycle again, it will fail.  Then again, and it will work. The work/
> not work pattern continues.  Even re-running the commitlog replay a 2nd time, without
> reloading the snapshot doesn't work
> The load process is:
> * Modify commitlog segment to 1mb
> * Archive to directory
> * create keyspace/table
> * insert base data
> * initial snapshot
> * write more data
> * capture timestamp
> * write more data
> * final snapshot
> * copy commitlogs to 2nd location
> * modify cassandra-env to replay only specified keyspace
> * modify commitlog properties to restore from 2nd location, with noted timestamp
> The restore cycle is:
> * truncate table
> * sstableload snapshot
> * flush
> * output data status
> * restart to replay commitlogs
> * output data status
> ====
> See attached .py for a mostly automated reproduction scenario.  It expects DSE (and I
found it with DSE 4.7.0-1), rather than "actual" Cassandra, but it's not using any DSE specific
features.  The script looks for the configs in the DSE locations, but they're set at the top,
and there's only 2 places where dse is restarted.



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