[
https://issues.apache.org/jira/browse/HBASE-5930?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13564097#comment-13564097
]
Lars Hofhansl commented on HBASE-5930:
--------------------------------------
Hmm... This is a bit more difficult than I thought.
I think what we want to limit is this: The maximum time an unflushed edit will
remain in the memstore. Otherwise one could trickle in edit 1 every hour and
get very old data in the memstore.
(Doing that could potentially also be cheaper as we do not need to retrieve the
current time on each edit, just the first one after a flush).
If that is true, then what we want track is not the time of the newest edit,
but the time of oldest unflushed edit, and flush if that gets too old.
In order to avoid flushing all memstores at the same time, we want to offset
the memstores flush times.
We can do it the way you have it.
(but it seems natural to me to do that at the place where we detect that the
memstore needs to be flushed. For this to work the chore needs to wake up more
frequently than the flush interval.)
Btw. the flush interval you have a 10mins, not 1h.
> Periodically flush the Memstore?
> --------------------------------
>
> Key: HBASE-5930
> URL: https://issues.apache.org/jira/browse/HBASE-5930
> Project: HBase
> Issue Type: Improvement
> Reporter: Lars Hofhansl
> Assignee: Devaraj Das
> Priority: Minor
> Fix For: 0.96.0
>
> Attachments: 5930-1.patch, 5930-2.1.patch, 5930-wip.patch
>
>
> 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.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
