[CALCITE-3629] Table-valued function implementor interface

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.22.0
• Assignee: Rui Wang
• Reporter: Rui Wang
• Created: 24/Dec/19 20:25
• Updated: 06/Mar/20 04:34
• Resolved: 15/Jan/20 05:20

Description

The current implementation of TUMBLE is the following:

if (isTumble()) {
   // create expressions and blockstatement
} else {
 // other table function scan enumerable implementation.
}

This style is less extensible. We will add more builtin table-valued function implementation and we shouldn't add more if-else with complicated implementation.

A better practice is in RexImpTable, each operator register its implementor, and then the code will be becomes:

if (implementor defined) {
   return implementor.implement(...)
}  else {
 // default table function scan enumerable implementation for those that does not have implementor.
} 

The current implementor[1] or [2] is not enough for table-valued function as table-valued function need both inputPhysType and outPhysType, and potential other params to implement itself.

Another condition is we might need more table-valued function implementations to abstract a common interface.

[1]: https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/adapter/enumerable/CallImplementor.java#L38
[2]: https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/adapter/enumerable/NotNullImplementor.java