Maybe the problem is the ‘build()’ after ‘as(“core”)’?
The alias is associated with entry on the RelBuilder stack, not the RelNode.
Once you have popped it, the alias is forgotten.
Julian
> On Jan 5, 2024, at 10:47, Eric Berryman <eric.berry...@gmail.com> wrote:
>
> I’m trying to use a union in a join, but I don’t see the alias as available
> (I get an error that the alias/field does not exist on the line of the
> below left join). The error shows available alias/fields and I see the
> union id fields but the alias is an empty set aliases:[]. Is this possible?
>
> Thank you!
> Eric
>
> List tableScans = new ArrayList<>();
>
> for (String tableName : tablesToUnion) {
> RelNode tableScan = builder
> .scan(tableName)
> .project(builder.field("id"), builder.field("field1"))
> .build();
> tableScans.add(tableScan);
> }
> // Use pushAll to add all table scans to the stack and create a UNION ALL
> builder.pushAll(tableScans);
> RelNode union = builder.union(true, tableScans.size());
>
> // Start with the union as the initial part of the join
> RelNode current = builder.push(union).as("core").build();
>
> // Iterate over the tables to join
> for (String joinTable : tablesToJoin) {
> current = builder
> .push(current)
> .scan(joinTable)
> .join(JoinRelType.LEFT,
> builder.equals( builder.field(2, "core", "id"),
> builder.field(joinTable, "id")))
> .project(builder.fields())
> .build();
> }
