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From "Rajesh Balamohan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-14423) S3: Fetching partition sizes from FS can be expensive when stats are not available in metastore
Date Fri, 05 Aug 2016 11:10:20 GMT

     [ https://issues.apache.org/jira/browse/HIVE-14423?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Rajesh Balamohan updated HIVE-14423:
------------------------------------
    Attachment: HIVE-14423.2.patch

> 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, HIVE-14423.2.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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