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From "Jesus Camacho Rodriguez (JIRA)" <j...@apache.org>
Subject [jira] [Work started] (HIVE-16957) Support CTAS for auto gather column stats
Date Wed, 12 Dec 2018 01:24:00 GMT

     [ https://issues.apache.org/jira/browse/HIVE-16957?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Work on HIVE-16957 started by Jesus Camacho Rodriguez.
------------------------------------------------------
> Support CTAS for auto gather column stats
> -----------------------------------------
>
>                 Key: HIVE-16957
>                 URL: https://issues.apache.org/jira/browse/HIVE-16957
>             Project: Hive
>          Issue Type: Sub-task
>            Reporter: Pengcheng Xiong
>            Assignee: Jesus Camacho Rodriguez
>            Priority: Major
>
> The idea is to rely as much as possible on the logic in ColumnStatsSemanticAnalyzer as
other operations do. In particular, they create a 'analyze table t compute statistics for
columns', use ColumnStatsSemanticAnalyzer to parse it, and connect resulting plan to existing
INSERT/INSERT OVERWRITE statement. The challenge for CTAS or CREATE MATERIALIZED VIEW is that
the table object does not exist yet, hence we cannot rely fully on ColumnStatsSemanticAnalyzer.
> Thus, we use same process, but ColumnStatsSemanticAnalyzer produces a statement for column
stats collection that uses a table values clause instead of the original table reference:
> {code}
> select compute_stats(col1), compute_stats(col2), compute_stats(col3)
> from table(values(cast(null as int), cast(null as int), cast(null as string))) as t(col1,
col2, col3);
> {code}



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