1. HBase
  2. HBASE-5229

Provide basic building blocks for "multi-row" local transactions.


    • Type: New Feature New Feature
    • Status: Closed
    • Priority: Major Major
    • Resolution: Fixed
    • Affects Version/s: None
    • Fix Version/s: 0.94.0
    • Component/s: Client, regionserver
    • Labels:
    • Hadoop Flags:


      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.

      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.

      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.

      1. 5229.txt
        27 kB
        Lars Hofhansl
      2. 5229-seekto.txt
        7 kB
        Lars Hofhansl
      3. 5229-seekto-v2.txt
        8 kB
        Lars Hofhansl
      4. 5229-multiRow.txt
        29 kB
        Lars Hofhansl
      5. 5229-multiRow-v2.txt
        25 kB
        Lars Hofhansl
      6. 5229-endpoint.txt
        20 kB
        Lars Hofhansl
      7. 5229-final.txt
        21 kB
        Lars Hofhansl

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            • Assignee:
              Lars Hofhansl
              Lars Hofhansl
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