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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-10201) Port 'Make flush decisions per column family' to trunk
Date Fri, 12 Dec 2014 01:17:14 GMT

    [ https://issues.apache.org/jira/browse/HBASE-10201?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14243546#comment-14243546
] 

stack commented on HBASE-10201:
-------------------------------

[~jeffreyz] I'm referring to the fact that if three column families, and one has edit #1,
another edit #2 (which came later) and the third had edit #3 and then if the policy decides
flush the third CF, we'll write it out with a seqid of #3 but edits #1 and #2 are still in
memory. We report to the master our lowest number is #1 but master crashes (so we lose info
that #1 is earliest safe edit number).  The RS hosting the three column famiilies also crashes.
 On recovery, we open the region and see a hfile with seqid #3 so we set the region current
seqid to #4.. even though #1 and #2 were never persisted.  This is possible with this patch
as is especially when policy is disconnected from flush.

bq. We need to pass flushed seqIds per store to master so that we can optimize recovery process
but doesn't impact correctness.

This would not fix the above case?  The master might know that #3 was persisted and that column
family 1 and 2 had edits less than #3 but if it crashes, we're back in the scenario described
above (unless we persist the flush reports?)

Thanks.


> Port 'Make flush decisions per column family' to trunk
> ------------------------------------------------------
>
>                 Key: HBASE-10201
>                 URL: https://issues.apache.org/jira/browse/HBASE-10201
>             Project: HBase
>          Issue Type: Improvement
>          Components: wal
>            Reporter: Ted Yu
>            Assignee: zhangduo
>             Fix For: 1.0.0, 2.0.0
>
>         Attachments: 3149-trunk-v1.txt, HBASE-10201-0.98.patch, HBASE-10201-0.98_1.patch,
HBASE-10201-0.98_2.patch, HBASE-10201-0.99.patch, HBASE-10201.patch, HBASE-10201_1.patch,
HBASE-10201_10.patch, HBASE-10201_11.patch, HBASE-10201_12.patch, HBASE-10201_13.patch, HBASE-10201_13.patch,
HBASE-10201_14.patch, HBASE-10201_15.patch, HBASE-10201_16.patch, HBASE-10201_17.patch, HBASE-10201_18.patch,
HBASE-10201_2.patch, HBASE-10201_3.patch, HBASE-10201_4.patch, HBASE-10201_5.patch, HBASE-10201_6.patch,
HBASE-10201_7.patch, HBASE-10201_8.patch, HBASE-10201_9.patch, compactions.png, count.png,
io.png, memstore.png
>
>
> Currently the flush decision is made using the aggregate size of all column families.
When large and small column families co-exist, this causes many small flushes of the smaller
CF. We need to make per-CF flush decisions.



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