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https://issues.apache.org/jira/browse/DRILL-6763?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16628279#comment-16628279
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Pritesh Maker commented on DRILL-6763:
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[~karthikm] could you take a look at this improvement? You might be more
familiar with codegen.
> Codegen optimization of SQL functions with constant values
> ----------------------------------------------------------
>
> Key: DRILL-6763
> URL: https://issues.apache.org/jira/browse/DRILL-6763
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Codegen
> Affects Versions: 1.14.0
> Reporter: shuifeng lu
> Assignee: shuifeng lu
> Priority: Critical
> Fix For: 1.15.0
>
> Attachments: Query1.java, Query2.java, code_compare.png,
> compilation_time.png
>
>
> Codegen class compilation takes tens to hundreds of milliseconds, a class
> cache is hit when generifiedCode of code generator is exactly the same.
> It works fine when UDF only takes columns or symbols, but not efficient when
> one or more parameters in UDF is always distinct from the other.
> Take face recognition for example, the face images are almost distinct from
> each other according to lighting, facial expressions and details.
> It is important to reduce redundant class compilation especially for those
> low latency queries.
> Cache miss rate and metaspace gc can also be reduced by eliminating the
> redundant classes.
> Here is the query to get the persons whose last name is Brunner and hire from
> 1st Jan 1990:
> SELECT full_name, hire_date FROM cp.`employee.json` where last_name =
> 'Brunner' and hire_date >= '1990-01-01 00:00:00.0';
> Now get the persons whose last name is Bernard and hire from 1st Jan 1990.
> SELECT full_name, hire_date FROM cp.`employee.json` where last_name =
> 'Bernard' and hire_date >= '1990-01-01 00:00:00.0';
> Figure !compilation_time.png! shows the compilation time of the generated
> code by the above query in FilterRecordBatch on my laptop
> Figure !code_compare.png! shows the only difference of the generated code
> from the attachments is the last_name value at line 156.
> It is straightforward that the redundant class compilation can be eliminated
> by making the string12 as a member of the class and set the value when the
> instance is created
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