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https://issues.apache.org/jira/browse/SPARK-17581?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sean Owen resolved SPARK-17581.
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Resolution: Not A Problem
> Invalidate Statistics After Some ALTER TABLE Commands
> -----------------------------------------------------
>
> Key: SPARK-17581
> URL: https://issues.apache.org/jira/browse/SPARK-17581
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.1.0
> Reporter: Xiao Li
>
> In the recent statistics-related work, our focus is on how to generate and
> store the statistics. After `Analyze Table` commands, the statistics will not
> be changed unless users run the command again. However, Hive behaves
> differently. For example, `ALTER TABLE SET LOCATION` will invalidate the
> statistics, including `numRows` and `rawDataSize`.
> {noformat}
> hive> describe formatted t2;
> ...
> Location: hdfs://6b68a24121f4:9000/user/hive/warehouse/t2
> Table Type: MANAGED_TABLE
> Table Parameters:
> COLUMN_STATS_ACCURATE true
> numFiles 4
> numRows 2
> rawDataSize 2
> totalSize 4
> transient_lastDdlTime 1464590855
> ...
> {noformat}
> {noformat}
> hive> alter table t2 set location
> 'hdfs://6b68a24121f4:9000/user/hive/warehouse/t1';
> OK
> Time taken: 0.113 seconds
> {noformat}
> {noformat}
> hive> describe formatted t2;
> ...
> Location: hdfs://6b68a24121f4:9000/user/hive/warehouse/t1
> Table Type: MANAGED_TABLE
> Table Parameters:
> COLUMN_STATS_ACCURATE false
> last_modified_by root
> last_modified_time 1474178025
> numFiles 4
> numRows -1
> rawDataSize -1
> totalSize 4
> ...
> {noformat}
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