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https://issues.apache.org/jira/browse/HBASE-5229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13202700#comment-13202700
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Lars Hofhansl commented on HBASE-5229:
--------------------------------------
@Todd: The last patch only provides a hook for a coprocessor endpoint to call
(and the hook itself is just a more flexible way to call an existing method).
So in order to use this, a user would need to write and install a coprocessor
endpoint.
Coprocessors can already do whatever they want, and that includes modifying
multiple rows (but this feature cannot be done efficiently or correctly, hence
the small core change).
Only HRegion is changed (20 lines without comments), the rest is test code.
> Explore building blocks for "multi-row" local transactions.
> -----------------------------------------------------------
>
> Key: HBASE-5229
> URL: https://issues.apache.org/jira/browse/HBASE-5229
> Project: HBase
> Issue Type: New Feature
> Components: client, regionserver
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Fix For: 0.94.0
>
> Attachments: 5229-endpoint.txt, 5229-multiRow-v2.txt,
> 5229-multiRow.txt, 5229-seekto-v2.txt, 5229-seekto.txt, 5229.txt
>
>
> HBase should provide basic building blocks for multi-row local transactions.
> Local means that we do this by co-locating the data. Global (cross region)
> transactions are not discussed here.
> After a bit of discussion two solutions have emerged:
> 1. Keep the row-key for determining grouping and location and allow efficient
> intra-row scanning. A client application would then model tables as
> HBase-rows.
> 2. Define a prefix-length in HTableDescriptor that defines a grouping of
> rows. Regions will then never be split inside a grouping prefix.
> #1 is true to the current storage paradigm of HBase.
> #2 is true to the current client side API.
> I will explore these two with sample patches here.
> --------------------
> Was:
> As discussed (at length) on the dev mailing list with the HBASE-3584 and
> HBASE-5203 committed, supporting atomic cross row transactions within a
> region becomes simple.
> I am aware of the hesitation about the usefulness of this feature, but we
> have to start somewhere.
> Let's use this jira for discussion, I'll attach a patch (with tests)
> momentarily to make this concrete.
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