[jira] [Updated] (CASSANDRA-5704) Truncate flushes to disk again in 1.2, even with durable_writes=false

["Christian Spriegel (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CASSANDRA-5704?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Christian Spriegel updated CASSANDRA-5704:
------------------------------------------

    Attachment: CASSANDRA_5704_V1.patch
    
> Truncate flushes to disk again in 1.2, even with durable_writes=false
> ---------------------------------------------------------------------
>
>                 Key: CASSANDRA-5704
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5704
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.2.5
>            Reporter: Christian Spriegel
>            Assignee: Christian Spriegel
>            Priority: Minor
>         Attachments: CASSANDRA_5704_V1.patch
>
>
> I just upgraded my dev-environment to C* 1.2. Unfortunetaly 1.2 makes my JUnit tests slow again, due to a blocking-flush in saveTruncationRecord().
> With Cassandra 1.1 truncate was very fast due to: CASSANDRA-4153
> My proposal is to make saveTruncationRecord() only flush when durableWrites are enabled.
> My assumption is that if somebody turn off durable writes then he does not mind if truncate is not guaranteed to be durable either.
> I successfully tested the following patch with my testsuite. Its as fast as it was with 1.1 (maybe even faster!):
> {code}
> @@ -186,5 +186,8 @@ public class SystemTable
>          String req = "UPDATE system.%s SET truncated_at = truncated_at + %s WHERE key = '%s'";
>          processInternal(String.format(req, LOCAL_CF, truncationAsMapEntry(cfs, truncatedAt, position), LOCAL_KEY));
> -        forceBlockingFlush(LOCAL_CF);
> +        
> +        KSMetaData ksm = Schema.instance.getKSMetaData(cfs.table.name);
> +        if (ksm.durableWrites) // flush only when durable_writes are enabled
> +            forceBlockingFlush(LOCAL_CF);
>      }
> {code}

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