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https://issues.apache.org/jira/browse/CALCITE-2703?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16720036#comment-16720036
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Stamatis Zampetakis commented on CALCITE-2703:
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[~hhlai1990], as it is the case for this optimization it can be beneficial
depending on the query workload. If you have big queries with many joins that
happen to appear very often it can be beneficial. On the other hand, if the
queries are very simple or if they don't appear often it will not bring much
benefit, rather the opposite.
> Reduce code generation and class loading overhead when executing queries in
> the EnumerableConvention
> ----------------------------------------------------------------------------------------------------
>
> Key: CALCITE-2703
> URL: https://issues.apache.org/jira/browse/CALCITE-2703
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.17.0
> Reporter: Stamatis Zampetakis
> Assignee: Julian Hyde
> Priority: Major
> Labels: performance
> Fix For: 1.18.0
>
>
> The queries using Calcite's EnumerableConvention always end-up generating new
> java classes at runtime (using Janino) that are then instantiated using
> reflection. This combination of class generation and class loading introduces
> a big overhead in query response time.
> A quick profiling on our Company's internal test suite consisting in 4000
> tests with roughly 430000 SQL queries passing through Calcite we observed
> that a big amount of time is spend on code generation and class loading
> making the EnumerableInterpretable#toBindable method a performance
> bottleneck.
> Among the 430000 SQL queries there are many duplicates which are going to
> lead to the generation of exactly the same code Java. Introducing, a small
> cache at the level of EnumerableInterpretable class could avoid generating
> and loading the same code over and over again.
> A simple implementation based on Guava improved the overall execution time of
> the afforementioned test suite by more than 50%.
>
>
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