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Julian Hyde commented on CALCITE-2302: -------------------------------------- Calcite already does some implicit conversions. I agree we could do more. Can you describe your use cases more fully? > Implicit type cast support > -------------------------- > > Key: CALCITE-2302 > URL: https://issues.apache.org/jira/browse/CALCITE-2302 > Project: Calcite > Issue Type: Improvement > Components: core > Affects Versions: 1.17.0 > Reporter: Yuzhao Chen > Assignee: Julian Hyde > Priority: Major > Fix For: 1.17.0 > > > Now many DBs have support implicit type cast, eg: SqlServer, Oracle, Hive. > Implicit type cast is an useful function for many cases, So we should support > this. > I checkout Calcite code and found that: > # Now we use a validator to validate our operands types[ through kinds of > namespaces and scopes ] > # Most of the validations will finally goes to > {code:java} > SqlOperator.validateOperands > {code} > # which will use validation logic defined in corresponding > SqlOperandTypeChecker > What i'm confused about is where should i put the implicit type cast logic > in? I figured out 2 ways: > # Supply a tool class/rules to add casts into a parsed SqlNode tree which > will then go through the validation logic later on. > # Unleash the validation logic in kinds of SqlOperandTypeChecker, then modify > the RelNode/RexNodes tree converted from a validated SqlNode tree to add in > casts through custom RelOptRules. > So guys, which of the 2 ways should i go, or if there are better way to do > this? > I need your help. -- This message was sent by Atlassian JIRA (v7.6.3#76005)