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https://issues.apache.org/jira/browse/HBASE-2175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12918202#action_12918202
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Jonathan Gray commented on HBASE-2175:
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JD, punt to 0.92?
> Investigate .META. slowdowns when more than 1 store files
> ---------------------------------------------------------
>
> Key: HBASE-2175
> URL: https://issues.apache.org/jira/browse/HBASE-2175
> Project: HBase
> Issue Type: Bug
> Reporter: Jean-Daniel Cryans
> Fix For: 0.90.0
>
>
> I'm currently testing Hadoop 0.21 with HBase trunk + HBASE-2066 by importing
> our main data set. After some time, probably because of log rolls which force
> flushes and a cluster restart, the .META. region begins to accumulate store
> files. I'm refreshing the master web UI a lot to see our insert speed and saw
> that 1) it was getting slower to refresh and 2) the import speed went down at
> the same time.
> Having already seen something like that previously with 0.20, I forced a
> major compaction on .META. and immediately the refresh speed got 10 times
> better and the import throughput went 2x (tasks went from 20 min to 10 min).
> Why is scanning and doing random reads from the client that slow when .META.
> has more than 1 store file? If it's a more fondamental speed issue, could we
> at least force major compactions on .META. when it grows so that the rest of
> the cluster doesn't get super slow? By the way, that operation takes less
> than 1 second since that region is so small.
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