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https://issues.apache.org/jira/browse/HBASE-5229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13193551#comment-13193551
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Lars Hofhansl commented on HBASE-5229:
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Is anybody interested in me exploring the split prefix idea described above?
Basically a table would declare a prefix of N bytes, and during splitting we
make sure don't split values with the same prefix (which essentially just means
that we calculate the midKey as we do now, and just take the first N bytes to
perform the actual split, hence actual split point would always be aligned with
the prefixes).
That way we have defined a grouping of rows that could participate in local
transactions.
> 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-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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