I suspect that the problem is this. Validation is mostly read-only but not entirely. When you validate the AST for ’select foo from t’ the validator mutates it as if the user had written ’select t.foo from t’. This makes SqlToRelConverter’s job easier/possible.
You are providing the AST for ‘bar + 1’ to SqlToRelConverter but it needs the AST for ’t.bar + 1' The easiest thing is to parse, validate, convert ’select bar + 1 from t’, then take the first RexNode in the resulting Project. > On Feb 21, 2023, at 3:12 PM, Guillaume Masse <[email protected]> > wrote: > > Hi All, > > I have a question regarding how to get a rex expression scoped to a select > list: > > Let's say I have a table t: > > CREATE TABLE t ( > foo int, > bar int > ); > > And a simple query: > > SELECT foo FROM t > > And some standalone expressions related to that query/table stored > elsewhere that I want to inject: > > bar + 123 > > Where the final desired query is: > > SELECT foo, bar + 123 FROM t > > How can I produce a RexNode for the expression `bar + 1` (eg `$1 + 123`)? > > My intuition was to validate the simple query and get the scope at the > select list: > > SqlValidator validator > SqlToRelConverter converter > > > SqlSelect select = (SqlSelect) parse("SELECT foo FROM t") > validator.validate(select) > > SqlNode node = parse("bar + 123") > val scope = validator.getSelectScope(select) > node.validateExpr(validator, scope) > > RexNode rex = converter.convertExpression(node) > > however, I can't get the identifier resolved. > [info] Cause: java.lang.AssertionError: no unique expression found for > {id: bar, prefix: 1}; count is 0 > [info] at > org.apache.calcite.sql2rel.SqlToRelConverter$Blackboard.lookupExp(SqlToRelConverter.java:5009) > [info] at > org.apache.calcite.sql2rel.SqlToRelConverter.convertIdentifier(SqlToRelConverter.java:4299) > [info] at > org.apache.calcite.sql2rel.SqlToRelConverter.access$2600(SqlToRelConverter.java:229) > [info] at > org.apache.calcite.sql2rel.SqlToRelConverter$Blackboard.visit(SqlToRelConverter.java:5532) > [info] at > org.apache.calcite.sql2rel.SqlToRelConverter$Blackboard.visit(SqlToRelConverter.java:4702) > [info] at > org.apache.calcite.sql.SqlIdentifier.accept(SqlIdentifier.java:324) > [info] at > org.apache.calcite.sql2rel.SqlToRelConverter$Blackboard.convertExpression(SqlToRelConverter.java:5351) > [info] at > org.apache.calcite.sql2rel.StandardConvertletTable.convertOperands(StandardConvertletTable.java:971) > [info] at > org.apache.calcite.sql2rel.StandardConvertletTable.convertOperands(StandardConvertletTable.java:963) > [info] at > org.apache.calcite.sql2rel.StandardConvertletTable.convertCall(StandardConvertletTable.java:916) > > > For the rest of the process (rebuilding the select with the new select > list), I have no problem. > > I'm really stuck with resolving identifiers given the scope of the select > list. > > Any help would be greatly appreciated. > > Guillaume Massé > 马赛卫
