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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8753) Provide new delete flag which can delete all cells under a column-family which have a same designated timestamp
Date Wed, 19 Jun 2013 08:44:22 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8753?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13687781#comment-13687781

Lars Hofhansl commented on HBASE-8753:

Will this break backwards-compatibility during rolling restarts? (because of the new KV type)
===> Yes, old RS bits will ignore DeleteFamilyVersion type KV written by new client.

This will only be an issue in two scenarios:
# An old RS replaying logs from a new RS that crashed during a rolling upgrade.
# A new HFile loaded by an old RS. (rebalance should be disabled during rolling restart, so
that should also only happen when a RS crashes during rolling restart).

It seems this is acceptable.
It is not immediately clear that won't be other issues during a rolling restart. Comments?

Otherwise +1 on patch.

Thanks for digging in on this, Feng.
> Provide new delete flag which can delete all cells under a column-family which have a
same designated timestamp
> ---------------------------------------------------------------------------------------------------------------
>                 Key: HBASE-8753
>                 URL: https://issues.apache.org/jira/browse/HBASE-8753
>             Project: HBase
>          Issue Type: New Feature
>          Components: Deletes
>            Reporter: Feng Honghua
>         Attachments: HBASE-8753-0.94-V0.patch, HBASE-8753-trunk-V0.patch
> In one of our production scenario (Xiaomi message search), multiple cells will be put
in batch using a same timestamp with different column names under a specific column-family.

> And after some time these cells also need to be deleted in batch by given a specific
timestamp. But the column names are parsed tokens which can be arbitrary words , so such batch
delete is impossible without first retrieving all KVs from that CF and get the column name
list which has KV with that given timestamp, and then issuing individual deleteColumn for
each column in that column-list.
> Though it's possible to do such batch delete, its performance is poor, and customers
also find their code is quite clumsy by first retrieving and populating the column list and
then issuing a deleteColumn for each column in that column-list.
> This feature resolves this problem by introducing a new delete flag: DeleteFamilyVersion.

>   1). When you need to delete all KVs under a column-family with a given timestamp, just
call Delete.deleteFamilyVersion(cfName, timestamp); only a DeleteFamilyVersion type KV is
put to HBase (like DeleteFamily / DeleteColumn / Delete) without read operation;
>   2). Like other delete types, DeleteFamilyVersion takes effect in get/scan/flush/compact
operations, the ScanDeleteTracker now parses out and uses DeleteFamilyVersion to prevent all
KVs under the specific CF which has the same timestamp as the DeleteFamilyVersion KV to pop-up
as part of a get/scan result (also in flush/compact).
> Our customers find this feature efficient, clean and easy-to-use since it does its work
without knowing the exact column names list that needs to be deleted. 
> This feature has been running smoothly for a couple of months in our production clusters.

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