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https://issues.apache.org/jira/browse/HIVE-23368?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17099641#comment-17099641
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Zoltan Haindrich commented on HIVE-23368:
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[~jcamachorodriguez] I've just thinked about fixing this - but then I realized
that it shouldn't even work "the best" with the rewrite:
if we have rewrites enabled:
{{count(distinct id)}} is rewritten to {{ds_hll_esitamte(ds_hll_sketch(id))}}
which is from the MV point of view just like an int as {{count(distinct id)}} -
so right now MV createrors should be aware if they want to create a sketch to
be used by the rewrite.
If we want to automatically do a partial rewrite (save the binary instead of a
plain int) - then we will most probably have a rule which changes the rowtype
of a relnode; which might be problematic.
So right now I think it is safe to use MVs with datasketches rewrite.
At the time I was writing the qtest I've created the view storing a
`ds_hll_sketch` of the input data; to enable rollups:
https://github.com/apache/hive/blob/5a119b9b556e1bfb0d7fdfcae2b5161b34d83f55/ql/src/test/queries/clientpositive/sketches_materialized_view_rollup2.q#L15
> MV rebuild should produce the same view as the one configured at creation time
> ------------------------------------------------------------------------------
>
> Key: HIVE-23368
> URL: https://issues.apache.org/jira/browse/HIVE-23368
> Project: Hive
> Issue Type: Sub-task
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
>
> There might be some configrations which might affect the rel-tree of the
> materialized views.
> In case rewrites to use datasketches for count(distinct) is enabled; the view
> should store sketches instead of distinct values
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