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https://issues.apache.org/jira/browse/HIVE-3917?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13564864#comment-13564864
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Gang Tim Liu commented on HIVE-3917:
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noscan is designed for fast operation. It doesn't require file scan. so all
statistics required by file scan are not collected. It includes number of rows,
columns stats etc.
Yes, we will introduce a flag which indicates stale information. will file a
follow up jira.
> Support fast operation for analyze command
> ------------------------------------------
>
> Key: HIVE-3917
> URL: https://issues.apache.org/jira/browse/HIVE-3917
> Project: Hive
> Issue Type: Improvement
> Components: Statistics
> Affects Versions: 0.11.0
> Reporter: Gang Tim Liu
> Assignee: Gang Tim Liu
> Attachments: HIVE-3917.patch.1
>
>
> hive supports analyze command to gather statistics from existing
> tables/partition
> https://cwiki.apache.org/confluence/display/Hive/StatsDev#StatsDev-ExistingTables
> It collects:
> 1. Number of Rows
> 2. Number of files
> 3. Size in Bytes
> If table/partition is big, the operation would take time since it will open
> all files and scan all data.
> It would be nice to support fast operation to gather statistics which doesn't
> require to open all files:
> 1. Number of files
> 2. Size in Bytes
> Potential syntax is
> ANALYZE TABLE tablename [PARTITION(partcol1[=val1], partcol2[=val2], ...)]
> COMPUTE STATISTICS [noscan];
> In the future, all statistics without scan can be retrieved via this optional
> parameter.
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