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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Created] (PHOENIX-4051) Prevent out-of-order updates for mutable index updates
Date Thu, 27 Jul 2017 23:10:00 GMT
James Taylor created PHOENIX-4051:
-------------------------------------

             Summary: Prevent out-of-order updates for mutable index updates
                 Key: PHOENIX-4051
                 URL: https://issues.apache.org/jira/browse/PHOENIX-4051
             Project: Phoenix
          Issue Type: Bug
            Reporter: James Taylor


Out-of-order processing of data rows during index maintenance causes mutable indexes to become
out of sync with regard to the data table. Here's a simple example to illustrate the issue:

# Assume table T(K,V) and index X(V,K).
# Upsert T(A, 1) at t10. Index updates: Put X(1,A) at t10.
# Upsert T(A, 3) at t30. Index updates: Delete X(1,A) at t29, Put X(3,A) at t30.
# Upsert T(A,2) at t20. Index updates: Delete X(1,A) at t19, Put X(2,A) at t20, Delete X(2,A)
at t29

Ideally, we'd want to remove the Delete X(1,A) at t29 since this isn't correct in terms of
timeline consistency, but we can't do that with HBase without support for deleting/undoing
Delete markers. 

The above is not what is occurring. Instead, when T(A,2) comes in, the Put X(2,A) will occur
at t20, but the Delete won't occur. This causes more index rows than data rows, essentially
making it invalid.

A quick fix is to reset the timestamp of the data table mutations to the current time within
the preBatchMutate call, when the row is exclusively locked. This skirts the issue because
then timestamps won't overlap.



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