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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2016/09/18 06:37:20 UTC
[jira] [Commented] (SPARK-17581) Invalidate Statistics After Some
ALTER TABLE Commands
[ https://issues.apache.org/jira/browse/SPARK-17581?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15500397#comment-15500397 ]
Apache Spark commented on SPARK-17581:
--------------------------------------
User 'gatorsmile' has created a pull request for this issue:
https://github.com/apache/spark/pull/15136
> 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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