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Posted to issues@hive.apache.org by "Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org> on 2017/11/28 18:52:00 UTC
[jira] [Comment Edited] (HIVE-18163) Stats: create materialized
view should also collect stats
[ https://issues.apache.org/jira/browse/HIVE-18163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16269240#comment-16269240 ]
Jesus Camacho Rodriguez edited comment on HIVE-18163 at 11/28/17 6:51 PM:
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[~kgyrtkirk], thanks for the patch.
Could we follow a different approach: would it be possible to put the view in the materialized view registry after StatsTask has run?
The problem with the approach in the patch is that we will load the materialized views in the cache at query planning time (when we call _getRewritingMaterializedViews_): we do not want to do that as it will put an additional burden on compilation time for queries (loading the query into the cache in fact parses the query, creates the Calcite logical plan, etc.).
was (Author: jcamachorodriguez):
[~kgyrtkirk], thanks for the patch.
Could we follow a different approach: would it be possible to put the view in the materialized view registry after StatsTask has run?
The problem with the approach in the patch is that we will load the materialized views in the cache at query planning time (when we call _getRewritingMaterializedViews_): we do not want to do that as it will put an additional burden on compilation time for queries (loading the query into the cache in fact parses the query, creates the Calcite logical plan, etc.). The assumption is that it is acceptable that the MV is not available immediately after creation for query rewriting.
> Stats: create materialized view should also collect stats
> ---------------------------------------------------------
>
> Key: HIVE-18163
> URL: https://issues.apache.org/jira/browse/HIVE-18163
> Project: Hive
> Issue Type: Sub-task
> Components: Statistics
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Attachments: HIVE-18163.01.patch
>
>
> not having basic stats on the materialized view may cause it to be "ruled out" as a viable alternative by the cbo.
> repro set {{set hive.stats.deserialization.factor=10.0}} in {{ql/src/test/queries/clientpositive/materialized_view_create_rewrite.q}}
> blocks: HIVE-18149
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