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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5762) Lost row marker after TTL expires
Date Mon, 15 Jul 2013 14:16:51 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13708490#comment-13708490
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Sylvain Lebresne commented on CASSANDRA-5762:
---------------------------------------------

This is a rather annoying problem. To sum it up, if you TTL one column, the row marker is
ttled too, because we have no way to know that this is not the last live column in that CQL3
row, but then if there was other non-ttled columns, they will survive the death of the row
marker which breaks the invariant that a live row always has a row marker.

Tbh, I have a hard time coming with a way to fix this. And so the only workaround that comes
to mind would be disallow setting a TTL on an individual columns. That is, you'd have to update
all columns of the row to be able to use a TTL, which I hate because 1) it'll look random
syntax wise and 2) I'm convinced that being able to TTL individual columns in a row is useful.
                
> Lost row marker after TTL expires
> ---------------------------------
>
>                 Key: CASSANDRA-5762
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5762
>             Project: Cassandra
>          Issue Type: Bug
>    Affects Versions: 1.2.6
>         Environment: Ubuntu 12.04
>            Reporter: Taner Catakli
>            Assignee: Sylvain Lebresne
>            Priority: Critical
>
> I have the following table
> cqlsh:loginproject> DESCRIBE TABLE gameservers;
>  
> CREATE TABLE gameservers (
>   address inet PRIMARY KEY,
>   last_update timestamp,
>   regions blob,
>   server_status boolean
> ) WITH
>   bloom_filter_fp_chance=0.010000 AND
>   caching='KEYS_ONLY' AND
>   comment='' AND
>   dclocal_read_repair_chance=0.000000 AND
>   gc_grace_seconds=864000 AND
>   read_repair_chance=0.100000 AND
>   replicate_on_write='true' AND
>   populate_io_cache_on_flush='false' AND
>   compaction={'class': 'SizeTieredCompactionStrategy'} AND
>   compression={'sstable_compression': 'SnappyCompressor'};
> after inserting a row and executing the following command:
> UPDATE gameservers USING TTL 10 SET server_status = true WHERE address = '192.168.0.100'
> after waiting for the ttl to expire, the row will lose its rowmarker making "select address
from gameservers" returning 0 results although there are some.
> in cassandra-cli the table looks like this:
> [default@loginproject] list gameservers;
> Using default limit of 100
> Using default cell limit of 100
> -------------------
> RowKey: 192.168.0.100
> => (name=last_update, value=0000000000000017, timestamp=1373884433543000)
> => (name=regions, value=<truncated>, timestamp=1373883701652000)
> 1 Row Returned.
> Elapsed time: 345 msec(s).
> [default@loginproject]

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