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https://issues.apache.org/jira/browse/CALCITE-3901?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated CALCITE-3901:
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Labels: pull-request-available (was: )
> Introduce an option to disable metadata handler regeneration
> ------------------------------------------------------------
>
> Key: CALCITE-3901
> URL: https://issues.apache.org/jira/browse/CALCITE-3901
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Liya Fan
> Priority: Major
> Labels: pull-request-available
>
> According to our investigation, Calcite can produce large performance
> overhead due to meta data handler regeneration.
> To illustrate, suppose we want to get the average size of a rel node, by
> calling the RelMetadataQuery#getAverageRowSize method. If the rel node type
> has not been registered before, JaninoRelMetadataProvider#revise method will
> be called, which will regerenate and recompile the code for the metadata
> handler.
> This process is time-consuming, as compiling code by Janino is
> time-consuming: It takes more than 10ms to compile a single source file, even
> if the file is small. According to our investigation, performance overhead
> due to this problem can be over 10% of the total optimization time.
> Therefore, we introduce an option to disable metadata handler regeneration.
> This forces the client to register all rel node types before calling the
> metadata service, so as to avoid performance being stolen silently.
> For some scenarios, the client mistakenly believes they have registered all
> rel node types, and this option helps them find the types they have missed.
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