[jira] [Commented] (HIVE-18743) CREATE TABLE on S3 data can be extremely slow. DO_NOT_UPDATE_STATS workaround is buggy.

["Jean-Yves STEPHAN (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-18743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17440502#comment-17440502 ] 

Jean-Yves STEPHAN commented on HIVE-18743:
------------------------------------------

Hello. We use Hive for a Spark project, and our Spark job hangs in a branch of the code controlled by the DO_NOT_POPULATE_QUICK_STATS property. I'd like to try switching off this flag, it's currently passed as an "EnvironmentContext". Is this something I can control via an environment variable? or via a HiveConf (to set in hive-site.xml)? 

> CREATE TABLE on S3 data can be extremely slow. DO_NOT_UPDATE_STATS workaround is buggy.
> ---------------------------------------------------------------------------------------
>
>                 Key: HIVE-18743
>                 URL: https://issues.apache.org/jira/browse/HIVE-18743
>             Project: Hive
>          Issue Type: Improvement
>          Components: Metastore
>    Affects Versions: 1.1.0, 1.2.0, 2.0.2, 3.0.0
>            Reporter: Alexander Behm
>            Assignee: Alex Kolbasov
>            Priority: Major
>             Fix For: 3.1.0, 2.4.0, 3.0.0
>
>         Attachments: HIVE-18743.01-branch-2.patch, HIVE-18743.01.patch
>
>
> When hive.stats.autogather=true then the Metastore lists all files under the table directory to populate basic stats like file counts and sizes. This file listing operation can be very expensive particularly on filesystems like S3.
> One way to address this issue is to reconfigure hive.stats.autogather=false.
> *Here's the bug*
> It is my understanding that the DO_NOT_UPDATE_STATS table property is intended to selectively prevent this stats collection. Unfortunately, this table property is checked *after* the expensive file listing operation, so the DO_NOT_UPDATE_STATS does not seem to work as intended. See:
> https://github.com/apache/hive/blob/master/standalone-metastore/src/main/java/org/apache/hadoop/hive/metastore/utils/MetaStoreUtils.java#L633
> Relevant code snippet:
> {code}
>   public static boolean updateTableStatsFast(Database db, Table tbl, Warehouse wh,
>                                              boolean madeDir, boolean forceRecompute, EnvironmentContext environmentContext) throws MetaException {
>     if (tbl.getPartitionKeysSize() == 0) {
>       // Update stats only when unpartitioned
>       FileStatus[] fileStatuses = wh.getFileStatusesForUnpartitionedTable(db, tbl);
>       return updateTableStatsFast(tbl, fileStatuses, madeDir, forceRecompute, environmentContext); <--- DO_NOT_UPDATE_STATS is checked in here after wh.getFileStatusesForUnpartitionedTable() has already been called
>     } else {
>       return false;
>     }
>   }
> {code}



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