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https://issues.apache.org/jira/browse/SPARK-21083?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhenhua Wang updated SPARK-21083:
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Description:
Suppose we already collected column stats for some columns before, then, when
we collect column stats for other columns:
* If the table is changed during two collecting actions, we need to remove
these stale column stats, only keep the latest stats.
* Otherwise, combine these two sets of column stats.
*
Note that we always update sizeInBytes/rowCount when collecting column stats,
that logic doesn't need change.
was:
Suppose we already collected column stats for some columns before, then, when
we collect column stats for other columns:
* If the table is changed during two collecting actions, we need to remove
these stale column stats, only keep the latest stats.
* Otherwise, combine these two sets of column stats.
Note that we always update sizeInBytes/rowCount when collecting column stats,
that logic doesn't need change.
> Consider staleness when collecting column stats
> -----------------------------------------------
>
> Key: SPARK-21083
> URL: https://issues.apache.org/jira/browse/SPARK-21083
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 2.3.0
> Reporter: Zhenhua Wang
>
> Suppose we already collected column stats for some columns before, then, when
> we collect column stats for other columns:
> * If the table is changed during two collecting actions, we need to remove
> these stale column stats, only keep the latest stats.
> * Otherwise, combine these two sets of column stats.
> *
> Note that we always update sizeInBytes/rowCount when collecting column stats,
> that logic doesn't need change.
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