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https://issues.apache.org/jira/browse/CALCITE-7362?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stamatis Zampetakis resolved CALCITE-7362.
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Fix Version/s: 1.42.0
Resolution: Fixed
Fixed in
[7654dd82162508231cb3ed44e60fed356e931403|https://github.com/apache/calcite/commit/7654dd82162508231cb3ed44e60fed356e931403].
Thanks for the reviews [~mbudiu] [~zhenchen] and [~asolimando] [~julianhyde]
for all the feedback and the helpful pointers.
> Add rule to transform WHERE clauses into filtered aggregates
> ------------------------------------------------------------
>
> Key: CALCITE-7362
> URL: https://issues.apache.org/jira/browse/CALCITE-7362
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Reporter: Stamatis Zampetakis
> Assignee: Stamatis Zampetakis
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.42.0
>
>
> Add a rule to transform aggregate queries with filtering based on {{WHERE}}
> clauses to filtered aggregates {{AGG(col) FILTER (WHERE)}} without a
> {{WHERE}} clause.
> The proposed transformation using the SQL representation is shown below:
> +Before+
> {code:sql}
> select sum(ss_net_paid_inc_tax)
> from store_sales
> where ss_quantity < 20
> {code}
> +After+
> {code:sql}
> select sum(ss_net_paid_inc_tax) filter (where ss_quantity < 20)
> from store_sales; {code}
> The queries are equivalent and the transformation is valid for all aggregate
> functions.
> The transformation is correct only when there is *no* GROUP BY clause (or
> GROUP BY ()).
> The main motivation for introducing this rule is view-based rewriting where
> it is quite common to have multiple conditional aggregates in the same
> (materialized) view definition for precomputing and reusing expensive
> aggregations.
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