Liya Fan created CALCITE-3901:
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Summary: 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
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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