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https://issues.apache.org/jira/browse/HIVE-17634?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16185362#comment-16185362
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Vineet Garg commented on HIVE-17634:
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Thanks for the clarification. I guess it makes sense. May be for large number
of columns user do turn this flag off and it'll be better in that case to have
estimated stats instead of no stats.
> Use properties from HiveConf about "fetchColStats" and "fetchPartStats" in
> RelOptHiveTable#updateColStats
> ---------------------------------------------------------------------------------------------------------
>
> Key: HIVE-17634
> URL: https://issues.apache.org/jira/browse/HIVE-17634
> Project: Hive
> Issue Type: Bug
> Reporter: liyunzhang_intel
> Assignee: liyunzhang_intel
> Attachments: HIVE-17634.patch
>
>
> in
> [RelOptHiveTable#updateColStats|https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/RelOptHiveTable.java#L309],
> we set {{fetchColStats}},{{fetchPartStats}} as true when call
> {{StatsUtils.collectStatistics}}
> {code}
> if (!hiveTblMetadata.isPartitioned()) {
> // 2.1 Handle the case for unpartitioned table.
> try {
> Statistics stats = StatsUtils.collectStatistics(hiveConf, null,
> hiveTblMetadata, hiveNonPartitionCols,
> nonPartColNamesThatRqrStats,
> colStatsCached, nonPartColNamesThatRqrStats, true, true);
> ...
> {code}
> This will cause querying columns statistic from metastore even we set
> {{hive.stats.fetch.column.stats}} and {{hive.stats.fetch.partition.stats}} as
> false in HiveConf. If we these two properties as false, we can not any
> column statistics from metastore. Suggest to set the properties from
> HiveConf.
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