scope of rex expressions

[Guillaume Masse]

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