SQL parser does not support schema-qualified table names

[fupelaqu]

Description

When using Apache Superset connected via Arrow Flight SQL, previewing a table triggers a query with a schema-qualified table name:

SELECT * FROM "default".ecommerce

The SQL parser cannot parse this syntax. Elasticsearch does not have a concept of schemas, but external tools (Superset, DBeaver, etc.) commonly prefix table names with a quoted schema (typically "default" or "information_schema").

Expected Behavior

The parser should accept schema-qualified identifiers in the form "schema".table (quoted schema only). For Elasticsearch, the schema component should be ignored and only the table name should be used.

Important: Only quoted schema prefixes are recognized. Unquoted dots are preserved as part of the Elasticsearch index name (e.g. logs-2025.03 remains logs-2025.03).

Reproduction

1. Start the demo with docker compose --profile superset-flight up
2. Open Superset at http://localhost:8088
3. Navigate to SQL Lab or preview a table in the default schema
4. Superset sends: SELECT * FROM "default".ecommerce
5. The Flight SQL server returns a parse error

Suggested Approach

• Add a quotedSchemaPrefix parser combinator in FromParser.scala that optionally matches a double-quoted string followed by . before the table name
• The quoted schema is discarded and only the table name is passed to the Table AST node