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https://issues.apache.org/jira/browse/HIVE-14423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15407573#comment-15407573
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Rajesh Balamohan commented on HIVE-14423:
-----------------------------------------
https://reviews.apache.org/r/50788/
> S3: Fetching partition sizes from FS can be expensive when stats are not
> available in metastore
> ------------------------------------------------------------------------------------------------
>
> Key: HIVE-14423
> URL: https://issues.apache.org/jira/browse/HIVE-14423
> Project: Hive
> Issue Type: Improvement
> Reporter: Rajesh Balamohan
> Assignee: Rajesh Balamohan
> Priority: Minor
> Attachments: HIVE-14423.1.patch
>
>
> When partition stats are not available in metastore, it tries to get the file
> sizes from FS.
> e.g
> {noformat}
> at
> org.apache.hadoop.fs.FileSystem.getContentSummary(FileSystem.java:1487)
> at
> org.apache.hadoop.hive.ql.stats.StatsUtils.getFileSizeForPartitions(StatsUtils.java:598)
> at
> org.apache.hadoop.hive.ql.stats.StatsUtils.collectStatistics(StatsUtils.java:235)
> at
> org.apache.hadoop.hive.ql.stats.StatsUtils.collectStatistics(StatsUtils.java:144)
> at
> org.apache.hadoop.hive.ql.stats.StatsUtils.collectStatistics(StatsUtils.java:132)
> at
> org.apache.hadoop.hive.ql.optimizer.stats.annotation.StatsRulesProcFactory$TableScanStatsRule.process(StatsRulesProcFactory.java:126)
> at
> org.apache.hadoop.hive.ql.lib.DefaultRuleDispatcher.dispatch(DefaultRuleDispatcher.java:90)
> at
> org.apache.hadoop.hive.ql.lib.DefaultGraphWalker.dispatchAndReturn(DefaultGraphWalker.java:105)
> {noformat}
> This can be quite expensive in some FS like S3. Especially when table is
> partitioned (e.g TPC-DS store_sales which has 1000s of partitions), query can
> spend 1000s of seconds just waiting for these information to be pulled in.
> Also, it would be good to remove FS.getContentSummary usage to find out file
> sizes.
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