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https://issues.apache.org/jira/browse/HBASE-9612?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13785590#comment-13785590
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stack commented on HBASE-9612:
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I spent time looking into trying to make [~eclark] less uncomfortable and doing
what [~tsuna] suggested a while back (perhaps off-issue), sorting out the
passed in actions into gets and mutations and then running a multiget for the
gets and a multi call for the mutations. Digging it seemed doable if I made
multiget look like multi; AsyncProcess has an executor pool so I was thinking I
could add one executor for the gets and another for the mutations per
regionserver. As long as I was careful w/ the results/exceptions keeping their
indexes running and aligned, I should be able to match up the returns before
giving it all back to the client.
But then I found the multiget has same issue as multirequest in that it only
allows a regions' worth of gets to run at a time against a server. Trying to
fix multiget, I was just reproducing the new multi model (a 'fixed' multiget
would have one or more per-region pbs to hold a set of Gets).
So, I am going to just remove multiGet. We only use it in one place inside in
the exists(List<Get>) call. If you want to do a multiget, you'll do this new
'universal' multi call.
Later, we can come along and add new methods to do multiGet and multiMutation
if worth the effort.
> Ability to batch edits destined to different regions
> ----------------------------------------------------
>
> Key: HBASE-9612
> URL: https://issues.apache.org/jira/browse/HBASE-9612
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.95.0, 0.95.1, 0.95.2, 0.96.0
> Reporter: Benoit Sigoure
> Assignee: stack
> Priority: Critical
> Fix For: 0.98.0, 0.96.0
>
> Attachments:
> 0001-fix-packaging-by-region-in-MultiServerCallable.patch, 9612.096.v5.txt,
> 9612revert.txt, 9612v10.txt, 9612v11.txt, 9612v12.txt, 9612v2.txt,
> 9612v3.txt, 9612v4.txt, 9612v5.txt, 9612v5.txt, 9612v5.txt, 9612v7.txt,
> 9612v8.096.txt, 9612v8.txt, 9612v9.txt, 9612v9.txt, 9612.wip.txt
>
>
> The old (pre-PB) "multi" and "multiPut" RPCs allowed one to batch edits
> destined to different regions. Seems like we've lost this ability after the
> switch to protobufs.
> The {{MultiRequest}} only contains one {{RegionSpecifier}}, and a list of
> {{MultiAction}}. The {{MultiAction}} message is contains either a single
> {{MutationProto}} or a {{Get}} (but not both – so its name is misleading as
> there is nothing "multi" about it). Also it seems redundant with
> {{MultiGetRequest}}, I'm not sure what's the point of supporting {{Get}} in
> {{MultiAction}}.
> I propose that we change {{MultiRequest}} to be a just a list of
> {{MultiAction}}, and {{MultiAction}} will contain the {{RegionSpecifier}},
> the {{bool atomic}} and a list of {{MutationProto}}. This would be a
> non-backward compatible protobuf change.
> If we want we can support mixing edits and reads, in which case we'd also add
> a list of {{Get}} in {{MultiAction}}, and we'd have support having both that
> list and the list of {{MutationProto}} set at the same time. But this is a
> bonus and can be done later (in a backward compatible manner, hence no need
> to rush on this one).
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