[jira] [Commented] (HBASE-11315) Keeping MVCC for configurable longer time

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

    [ https://issues.apache.org/jira/browse/HBASE-11315?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14049390#comment-14049390 ] 

stack commented on HBASE-11315:
-------------------------------

isAllFiles is bad name for a param.  Should be allFiles.  Or majorCompaction?  Would we ever want to keep sequenceid forever?  Patch looks good to me.



> Keeping MVCC for configurable longer time 
> ------------------------------------------
>
>                 Key: HBASE-11315
>                 URL: https://issues.apache.org/jira/browse/HBASE-11315
>             Project: HBase
>          Issue Type: Improvement
>    Affects Versions: 0.99.0
>            Reporter: Jeffrey Zhong
>            Assignee: Jeffrey Zhong
>         Attachments: hbase-11315.patch
>
>
> After hbase-8763, we need keep mvcc number longer in hfile so that it can be used to order changes during writes. For example, the known put,delete,put,... scenario, cross region server scan, out of order puts(in recovery case).
> Current thinking is that we make the retention period configurable(below we're using 1 day to explain). During major compaction, we check hfile's creation time if a hfile creation time is older than 1 day then all mvcc of KVs in that hfile will be removed. If a hfile is created within 1 day, then all mvccs of KVs in that hfile will be kept. 
> In case there are time clock skew, we can firstly sort hfiles based on its seqId in ascending order and find the first hfile's creation time stamp less than 1 day. Then mvcc of all hfiles before the found file will be removed during compaction. 



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