shivarajugowda opened a new issue, #1100:
URL: https://github.com/apache/arrow-java/issues/1100
### Describe the enhancement requested
Please expose Arrow `Struct` columns as JDBC `STRUCT` metadata in the Flight
SQL JDBC driver.
Today, Arrow `Struct` is mapped to `java.sql.Types.JAVA_OBJECT`, which
makes
`ResultSetMetaData` report:
- `getColumnType(...) == Types.JAVA_OBJECT`
- `getColumnTypeName(...) == "JAVA_OBJECT"`
This hides the fact that the column is structurally a JDBC `STRUCT`, even
though the driver
already has struct-specific accessor support.
## Why this matters
JDBC clients often rely on `ResultSetMetaData` to understand result
schemas before reading
rows. When `STRUCT` columns are reported as `JAVA_OBJECT`, clients cannot
distinguish:
- struct/object-like columns
- generic opaque objects
This makes schema inspection, BI tooling, ORM adapters, and generic JDBC
consumers harder.
## Current upstream evidence
In
`flight/flight-sql-jdbc-core/src/main/java/org/apache/arrow/driver/jdbc/utils/SqlTypes.java`:
- `ArrowType.Struct` maps to `Types.JAVA_OBJECT`
In
`flight/flight-sql-jdbc-core/src/main/java/org/apache/arrow/driver/jdbc/accessor/impl/comple
x/ArrowFlightJdbcStructVectorAccessor.java`:
- `getStruct()` is already implemented
- but `getObjectClass()` returns `Map.class`
- `getObject()` returns a `Map`
So the data path knows about structs, but metadata does not expose them
as JDBC `STRUCT`.
## Expected behavior
For Arrow `Struct` columns:
- `ResultSetMetaData.getColumnType(...)` should return
`java.sql.Types.STRUCT`
- `ResultSetMetaData.getColumnTypeName(...)` should return `STRUCT`
Optionally, `getObject()` / object-class behavior could also be aligned
with JDBC `Struct`, but
the most important gap is metadata.
## Actual behavior
Arrow `Struct` columns are exposed as:
- `Types.JAVA_OBJECT`
- `"JAVA_OBJECT"`
## Version
Observed with:
- Arrow Flight SQL JDBC driver `18.2.0`
Confirmed in current upstream code and latest published artifact line:
- `19.0.0`
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