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From "Bryan Duxbury (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-2) hlog numbers should wrap around when they reach 999
Date Thu, 07 Feb 2008 20:29:09 GMT

    [ https://issues.apache.org/jira/browse/HBASE-2?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12566781#action_12566781
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Bryan Duxbury commented on HBASE-2:
-----------------------------------

No question that a long is "overkill" for representing the number of .dat files we'll have.
However, we selected System.currentTimeMillis() because it would give us a unique, increasing
number every time. Storing an additional 7-10 bytes per filename seems like a reasonable tradeoff.


As far as the question of zero-fill, it's actually pretty moot, because it will only matter
when the length of the timestamps increases by a full order of magnitude. For today, that
means going from around 1.2 billion seconds since epoch to 10 billion seconds since epoch,
which is about 300 years from now. Even then, the problem would only manifest if two log files
were created across the 10 billion rollover. Do you think that we can be ok with a 1-second
danger zone 300 years from now?

> hlog numbers should wrap around when they reach 999
> ---------------------------------------------------
>
>                 Key: HBASE-2
>                 URL: https://issues.apache.org/jira/browse/HBASE-2
>             Project: Hadoop HBase
>          Issue Type: Bug
>          Components: regionserver
>            Reporter: Billy Pearson
>            Assignee: Bryan Duxbury
>            Priority: Minor
>             Fix For: 0.2.0
>
>         Attachments: 2-v2.patch, 2.patch
>
>
> Question about log numbers -> Closing current log writer hdfs://10.0.0.1:9000/gfs_storage/hadoop-root/hbase/log_10.0.0.3_1201900440436_60020/hlog.dat.024
> What happens when the log get to hlog.dat.999

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