[jira] [Commented] (HBASE-5930) Periodically flush the Memstore?

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

    [ https://issues.apache.org/jira/browse/HBASE-5930?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13410457#comment-13410457 ] 

nkeywal commented on HBASE-5930:
--------------------------------

I also think that a periodic memstore flush. Even with a WAL, it's seems safer/more efficient.
It seems that HBase had this a long long time ago:

{noformat}
  <property>
    <name>hbase.regionserver.optionalcacheflushinterval</name>
    <value>1800000</value>
    <description>
    Amount of time to wait since the last time a region was flushed before
    invoking an optional cache flush (An optional cache flush is a
    flush even though memcache is not at the memcache.flush.size).
    Default: 30 minutes (in miliseconds)
    </description>
  </property>
{noformat}

It could also be linked to major compactions (before a major compaction, flush 'old' memstore)?
                
> Periodically flush the Memstore?
> --------------------------------
>
>                 Key: HBASE-5930
>                 URL: https://issues.apache.org/jira/browse/HBASE-5930
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Lars Hofhansl
>            Priority: Minor
>
> A colleague of mine ran into an interesting issue.
> He inserted some data with the WAL disabled, which happened to fit in the aggregate Memstores memory.
> Two weeks later he a had problem with the HDFS cluster, which caused the region servers to abort. He found that his data was lost. Looking at the log we found that the Memstores were not flushed at all during these two weeks.
> Should we have an option to flush memstores periodically. There are obvious downsides to this, like many small storefiles, etc.

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