[CALCITE-2982] SqlItemOperator should throw understandable exception message for incorrect operand type

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.20.0
• Component/s: core
• Labels: pull-request-available
• Assignee: pengzhiwei
• Reporter: pengzhiwei
• Created: 08/Apr/19 06:36
• Updated: 24/Jun/19 15:01
• Resolved: 26/Apr/19 03:40

Description

In the following sql:

select name[0] from dept

name is a field of VARCHAR type, the follow exception message is thrown out:

java.lang.AssertionError: VARCHAR
at org.apache.calcite.sql.fun.SqlItemOperator.getChecker(SqlItemOperator.java:109)
at org.apache.calcite.sql.fun.SqlItemOperator.checkOperandTypes(SqlItemOperator.java:91)
at org.apache.calcite.sql.SqlOperator.validateOperands(SqlOperator.java:432)
at org.apache.calcite.sql.SqlOperator.deriveType(SqlOperator.java:516)
at org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:5607)
at org.apache.calcite.sql.validate.SqlValidatorImpl$DeriveTypeVisitor.visit(SqlValidatorImpl.java:5594)
at org.apache.calcite.sql.SqlCall.accept(SqlCall.java:139)

The exception message is hard to understand  for user. I think a message like "Cannot apply item opeator to VARCHAR type for filed "name"  at line xx column xx " is more friendly to the user.

Issue Links

• links to: GitHub Pull Request #1149