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https://issues.apache.org/jira/browse/DRILL-298?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mehant Baid resolved DRILL-298.
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Resolution: Fixed
Merged as b2263f9bb307d0119317418de183d0e2822757e7
> Extend Optiq's SqlOperatorTable to support Drill's custom functions
> -------------------------------------------------------------------
>
> Key: DRILL-298
> URL: https://issues.apache.org/jira/browse/DRILL-298
> Project: Apache Drill
> Issue Type: Bug
> Reporter: Mehant Baid
> Assignee: Mehant Baid
>
> One approach is to implement DrillSqlOperatorTable which extends Optiq's
> ReflectiveSqlOperatorTable. Optiq has a notion of chained operator table with
> which we can simply add our specific operator table (DrillSqlOperatorTable)
> to its existing operator tables such that Optiq recognizes all functions
> defined in DrillSqlOperatorTable.
> The main requirement of this task is to not have yet another set of
> declaration of functions, we want to automatically declare Drill's custom
> functions in a format understood by Optiq.
> Below is the task breakdown:
> 1. Registering of drill functions should take place before we register
> Optiq's functions. (This can be done as part of the "thinning out the JDBC
> client" task)
> 2. Once we have a set of registered functions in Drill, we need to go through
> them and define them using Optiq's syntax (using SqlFunction() for example)
> 3. Plugin DrillSqlOperatorTable into Optiq's ChainedSqlOperatorTable.
> One minor challenge might be to get around the way ReflectiveSqlOperatorTable
> works. ReflectiveSqlOperatorTable gets all the fields defined in the derived
> class (all fields in the derived class are operators or functions that need
> to be registered, eg: SqlStdOperatorTable) and adds it to a Map which it uses
> later to verify if the function/ operator exists. We need to come up with a
> way to automatically define these fields so that ReflectiveSqlOperatorTable
> picks them up.
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