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https://issues.apache.org/jira/browse/HIVE-18743?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16372504#comment-16372504
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Alexander Kolbasov commented on HIVE-18743:
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I think it makes sense to separate these - removal looks to be a more involved
problem. I don't have enough understanding of potential consequences.
> 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: 1.2.0, 1.1.0, 2.0.2, 3.0.0
> Reporter: Alexander Behm
> Assignee: Alexander Kolbasov
> Priority: Major
> Attachments: HIVE-18743.01.patch, HIVE-18743.02.patch,
> HIVE-18743.03.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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