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Posted to issues@trafodion.apache.org by "Alice Chen (JIRA)" <ji...@apache.org> on 2015/07/22 20:18:14 UTC

[jira] [Created] (TRAFODION-802) LP Bug: 1398600 - Performance regression from QI DDL phase 1

Alice Chen created TRAFODION-802:
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             Summary: LP Bug: 1398600 - Performance regression from QI DDL phase 1
                 Key: TRAFODION-802
                 URL: https://issues.apache.org/jira/browse/TRAFODION-802
             Project: Apache Trafodion
          Issue Type: Bug
          Components: sql-exe
            Reporter: Apache Trafodion
            Assignee: Apache Trafodion


Gary Hall has described path length regression of > 10% in the Nov15 nightly build, when running the YCSB Singleton Update benchmark, and similar regressions in a wide variety of workloads. Throughput was impacted around 5% also. 

Mike made him a UTT based on the Nov 14 nightly build with only the change from Ie61ce751089b57ce1894f1764c338e9400bb7b8a <https://review.trafodion.org/#/c/693/> back-ported which demonstrated that the "Query Invalidation triggered by DDL, phase 1" is responsible.

More UTTs and testing showed the problem was in the code that moves object UIDs into root tdbs -- when the table is SB_HISTOGRAMS or SB_HISTOGRAMS_INTERVALS. For these tables, getting the object UIDs requires special metadata lookups which weren't present before the change in question.
Assigned to LaunchPad User Mike Hanlon



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