[jira] [Created] (PHOENIX-5836) The first concurrent mutation may not be considered as concurrent

["Kadir OZDEMIR (Jira)" <ji...@apache.org>]

Kadir OZDEMIR created PHOENIX-5836:
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             Summary: The first concurrent mutation may not be considered as concurrent
                 Key: PHOENIX-5836
                 URL: https://issues.apache.org/jira/browse/PHOENIX-5836
             Project: Phoenix
          Issue Type: Improvement
    Affects Versions: 4.14.3, 5.0.0
            Reporter: Kadir OZDEMIR
            Assignee: Kadir OZDEMIR


From the consistent indexing design (PHOENIX-5156) perspective, two or more pending updates from different batches on the same data row are concurrent if and only if for all of these updates the data table row state is read from HBase under the row lock and for none of them the row lock has been acquired the second time for updating the data table. In other words, all of them are in the first update phase concurrently. For concurrent updates, the first two update phases are done but the last update phase is skipped. This means the data table row will be updated by these updates but the corresponding index table rows will be left with the unverified status. Then, the read repair process will repair these unverified index rows during scans.

However, if a concurrent mutation acquires the lock for reading the data row before any other concurrent mutations on this mutation, and also acquires the lock for updating the data row before any other mutations, this mutation can be treated as non-concurrent, and the third update phase can be executed safely for this mutation. Doing this will reduce the number of unverified rows due to concurrent mutations. 



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