[Java][FlightSQL] Inconsistent GET_PRIMARY_KEYS_SCHEMA

[devinrsmith]

Describe the bug, including details regarding any error messages, version, and platform.

The protobuf documentation ¹ for the returned schema of FlightSQL CommandGetPrimaryKeys is

 *  catalog_name: utf8,
 *  db_schema_name: utf8,
 *  table_name: utf8 not null,
 *  column_name: utf8 not null,
 *  key_name: utf8,
 *  key_sequence: int32 not null

org.apache.arrow.flight.sql.FlightSqlProducer.Schemas#GET_PRIMARY_KEYS_SCHEMA ² is defined as

    public static final Schema GET_PRIMARY_KEYS_SCHEMA =
        new Schema(asList(
            Field.nullable("catalog_name", VARCHAR.getType()),
            Field.nullable("db_schema_name", VARCHAR.getType()),
            Field.notNullable("table_name", VARCHAR.getType()),
            Field.notNullable("column_name", VARCHAR.getType()),
            Field.notNullable("key_sequence", INT.getType()),
            Field.nullable("key_name", VARCHAR.getType())));

Note the reordering of key_name and key_sequence.

Should this be considered a bug in the implementation or the documentation? Or, is field order "unimportant" in this context?

Component(s)

Java

Footnotes

1. https://github.com/apache/arrow/blob/apache-arrow-17.0.0/format/FlightSql.proto#L1280-L1285 ↩

2. https://github.com/apache/arrow/blob/apache-arrow-17.0.0/java/flight/flight-sql/src/main/java/org/apache/arrow/flight/sql/FlightSqlProducer.java#L1164-L1172 ↩

[lidavidm]

C++ agrees with Java:

arrow/cpp/src/arrow/flight/sql/server.cc

Lines 1302 to 1308 in 2bbd67d

	const std::shared_ptr<Schema>& SqlSchema::GetPrimaryKeysSchema() {
	static std::shared_ptr<Schema> kSchema = arrow::schema(
	{field("catalog_name", utf8()), field("db_schema_name", utf8()),
	field("table_name", utf8(), false), field("column_name", utf8(), false),
	field("key_sequence", int32(), false), field("key_name", utf8())});
	return kSchema;
	}

So does Go:

https://github.com/apache/arrow-go/blob/56b794f52a9bfb45fb54a4e070002a69b38fb018/arrow/flight/flightsql/schema_ref/reference_schemas.go#L46-L53

I'd consider this a bug in the documentation.

[lidavidm]

Transferred this back since I believe it is a documentation bug.

[lidavidm]

@jduo might you have any comments here? If the order in the source code is correct, does this documentation comment also need to be updated?

 * The returned data should be ordered by catalog_name, db_schema_name, table_name, key_name, then key_sequence.