Agree with Julian, RexProgram could do this work. I did this before in physical codegen based on Calc's RexProgram, and it works very well.
Julian Hyde <[email protected]> 于2022年7月14日周四 23:21写道： > It seems that you are tackling common scalar expressions (RexNodes) > whereas, based on the name the other rule is dealing with common relational > expressions (RelNode). > > For your rule, consider using RexProgram, RexProgramBuilder, and Calc. > They already convert a list of expressions to a DAG, so that no expression > is calculated more than once. > > Julian > > > On Jul 14, 2022, at 06:31, Jiajun Xie <[email protected]> wrote: > > > > Hello, all~ > > I am writing an RelOptRule that is for CommonSubExpressions. Here is an > > example that I completed. > > sql: `select sal, sal * 12, sal * 3, sal * 12 + sal * 3 from emp` > > planBefore: ```LogicalProject(SAL=[$5], EXPR$1=[*($5, 12)], > > EXPR$2=[*($5, 3)], EXPR$3=[+(*($5, 12), *($5, 3))]) > > LogicalTableScan(table=[[CATALOG, SALES, EMP]])``` > > planAfter: ```LogicalProject(SAL=[$0], EXPR$1=[$1], EXPR$2=[$2], > > EXPR$3=[+($1, $2)]) > > LogicalProject(SAL=[$5], CSE$0=[*($5, 12)], CSE$1=[*($5, 3)]) > > LogicalTableScan(table=[[CATALOG, SALES, EMP]])``` > > I found a RelOptRule that is named as CommonRelSubExprRule, but it is > > abstract. I wonder if anyone has implemented it? Is it the same as what I > > am doing? > > Thanks very much~ > -- Best, Benchao Li
