[CALCITE-3331] Support implicit type cast for operators that use single operand family checker

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.20.0
• Fix Version/s: 1.22.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Danny Chen
• Reporter: Danny Chen
• Created: 09/Sep/19 08:43
• Updated: 06/Mar/20 04:34
• Resolved: 12/Sep/19 02:26

Description

When the FamilyOperandTypeChecker is used to check single operand data type, support implicit type coercion if we can.

Now some of the sql operator override method #checkOperandTypes, and use the SqlSingleOperandTypeChecker#checkSingleOperandType to check the operand data type, we should support the implicit type coercion for these operators.

One impl that need to note:

we seem always pass the "iformalOperand" as "0" with method SqlSingleOperandTypeChecker#checkSingleOperandType when check the single operand, we need to pass in the real operand index in the call to the checker.

 

Final solution:

Caution that we could not(shouldn't) implement implicit type coercion for this checker,
implicit type coercion has side effect(modify the AST), if this single operand checker is
subsumed in a composite rule(OR or AND), we can not make any side effect if we
can not make sure that all the single operands type check are passed(with type coercion).
But there is an exception: only if the call has just one operand, for this case,
use {@link SqlOperandTypeChecker#checkOperandTypes} instead.

We decide to fix these operators separately.

Issue Links

• is related to: CALCITE-2302 Implicit type cast support
• links to: GitHub Pull Request #1450