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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/765/
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Review request for hive.
Summary
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Currently, the JDBCStatsPublisher executes two queries per inserted row of
statistics, first query to check if the ID was inserted by another task, and
second query to insert a new or update the existing row.
The latter occurs very rarely, since duplicates most likely originate from
speculative failed tasks.
Currently the schema of the stat table is the following:
PARTITION_STAT_TABLE ( ID VARCHAR(255), ROW_COUNT BIGINT ) and does not have
any integrity constraints declared.
We amend it to:
PARTITION_STAT_TABLE ( ID VARCHAR(255) PRIMARY KEY , ROW_COUNT BIGINT ).
HIVE-2144 improves on performance by greedily performing the insertion
statement.
Then instead of executing two queries per row inserted, we can execute one
INSERT query.
In the case primary key constraint violation, we perform a single UPDATE query.
The UPDATE query needs to check the condition, if the currently inserted stats
are "newer" then the ones already in the table.
This addresses bug HIVE-2144.
https://issues.apache.org/jira/browse/HIVE-2144
Diffs
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trunk/ql/src/java/org/apache/hadoop/hive/ql/stats/jdbc/JDBCStatsPublisher.java
1125140
trunk/ql/src/test/org/apache/hadoop/hive/ql/exec/TestStatsPublisher.java
PRE-CREATION
Diff: https://reviews.apache.org/r/765/diff
Testing
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TestStatsPublisher JUnit test:
- basic behaviour
- multiple updates
- cleanup of the statistics table after aggregation
Standalone testing on the cluster.
- insert/analyze queries over non-partitioned/partitioned tables
NOTE. For the correct behaviour, the primary_key index needs to be created, or
the PARTITION_STAT_TABLE table dropped - which triggers creation of the table
with the constraint declared.
Thanks,
Tomasz
