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From "Lars Hofhansl (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-5229) Provide basic building blocks for "multi-row" local transactions.
Date Wed, 08 Feb 2012 00:23:03 GMT

     [ https://issues.apache.org/jira/browse/HBASE-5229?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Lars Hofhansl updated HBASE-5229:
---------------------------------

    Description: 
In the final iteration, this issue provides a generalized, public mutateRowsWithLocks method
on HRegion, that can be used by coprocessors to implement atomic operations efficiently.
Coprocessors are already region aware, which makes this is a good pairing of APIs. This feature
is by design not available to the client via the HTable API.

It took a long time to arrive at this and I apologize for the public exposure of my (erratic
in retrospect) thought processes.

Was:
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.

  was:
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.

        Summary: Provide basic building blocks for "multi-row" local transactions.  (was:
Explore building blocks for "multi-row" local transactions.)
    
> Provide basic 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
>
>
> In the final iteration, this issue provides a generalized, public mutateRowsWithLocks
method on HRegion, that can be used by coprocessors to implement atomic operations efficiently.
> Coprocessors are already region aware, which makes this is a good pairing of APIs. This
feature is by design not available to the client via the HTable API.
> It took a long time to arrive at this and I apologize for the public exposure of my (erratic
in retrospect) thought processes.
> Was:
> 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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