Thanks Danny for pushing this. Just like you said, different engines may use different strategies for implicit type cast, so i think making the whole mechanism pluggable would be a good idea.
Best, Kurt On Mon, May 27, 2019 at 11:08 AM Haisheng Yuan <[email protected]> wrote: > Thanks Danny for bringing it up. > This is a useful feature, we should push it forward. > > I went through the design doc, looks good in general. > I will also spend some time on the pull request 706. > > Thanks ~ > Haisheng Yuan > ------------------------------------------------------------------ > 发件人：Yuzhao Chen<[email protected]> > 日 期：2019年05月27日 10:20:47 > 收件人：<[email protected]> > 主 题：Support complete implicit type coercion (DISCUSSION) > > Hi, guys. > > The implicit type coercion is almost supported by every production > RDBMS(MYSQL[1], ORACLE[2], SQLSERVER[3]), also some Hadoop data warehouse > facilitates like HIVE. > > As a query optimization engine of many comutation engines(like Apache > Flink) and some OLAP engines(like Apache Drill), Calcite would supply > better compatibility for sql query for the underlying engines it adapter > with with implicit type coercion. There are already some jira issues that > are relative with this topic more or less: > > 1. CALCITE-2992: Enhance implicit conversions when generating hash join > keys for an equiCondition > 2. CALCITE-3002: Case statement fails with: SqlValidatorException: Cannot > apply '=' to arguments of type '<INTEGER> = <BOOLEAN>' > 3. CALCITE-1531: SqlValidatorException when boolean operators are used > with NULL > 4. CALCITE-3081: https://issues.apache.org/jira/browse/CALCITE-3081 > 5. CALCITE-2829: Use consistent types when processing ranges > > I have fired a issue CALCITE-2302 [4] about 1 year ago, with a design > doc(sowehow rough). > > Maybe we should fire a new discussion here, and hope for your suggesions :) > > [1] https://dev.mysql.com/doc/refman/5.5/en/type-conversion.html > [2] > https://docs.oracle.com/cd/B12037_01/server.101/b10759/sql_elements002.htm > [3] > https://docs.microsoft.com/en-us/sql/t-sql/data-types/data-type-conversion-database-engine?view=sql-server-2017 > [4] https://issues.apache.org/jira/browse/CALCITE-2302 > [5] > https://docs.google.com/document/d/1g2RUnLXyp_LjUlO-wbblKuP5hqEu3a_2Mt2k4dh6RwU/edit#heading=h.77f83nidn37j > > Best, > Danny Chan > >
