jdbc: map Tarantool/SQL types into JDBC/Java types

[Totktonada]

Tarantool 2.1 now support static types. Currently supported types are described on wiki. We need to map Tarantool/SQL types to JDBC types in DatabaseMetaData.getColumns, ResultSetMetaData.getColumnType and other related methods.

[Totktonada]

INTEGER Tarantool/SQL type is wider then long Java type. We need to provide (and test) ability to set prepared statement values to, say, 2^64 and read such value from result set. A community people says a user can use setString() or setObject() to provide big integer value, so we need to support (and test) such cases. I think we also can provide more natural API with a method like setBigInteger().

[Totktonada]

Related: #27.

[Totktonada]

See also #130 and tarantool/tarantool#4019

[Totktonada]

Boolean was instroduced in 2.2: tarantool/tarantool#3648

[Totktonada]

Note: A SCALAR field can hold types other then msgpack bin. We need to handle and test this appropriately.

[Totktonada]

See #209 and #210 re integer types in tarantool-2.2.

[Totktonada]

See #214 re VARBINARY type in tarantool-2.2.

[Totktonada]

We should consider the commit 2.2.0-632-g36bdfbb24 ('sql: rename REAL/FLOAT/DOUBLE types to NUMBER') which is first released in tarantool-2.2.1. There is no good way to determine whether REAL/FLOAT/DOUBLE is supported or NUMBER. @kostja says we should drop support for tarantool versions below 2.2.1 in the scope of JDBC work. Maybe this is the only good way to handle this.

[Totktonada]

We discussed a bit the problem with floating point types. I suggest to do the following:

• Consider real/float/double as pure floating point types: as if they cannot store integral values—at least from metainfo point of view. Insert 2, select 2 should work I think. Enable tests for them on 2.1.
• Support 'number' on 2.2.1 and above. Disable float/real/double on 2.2.0 and above.
• State that all currently supported JDBC features should work since tarantool-2.2.1 in a next release notes for tarantool-java.

[Totktonada]

See also tarantool/tarantool@b7d595a

[nicktorwald]

In scope of #218 the following things were done:

1. Support BOOL / BOOLEAN type (according to sql: introduce type <Boolean> tarantool#3648)
2. Support UNSIGNED type (jdbc: support UNSIGNED type #210, sql: support UNSIGNED type tarantool#4015)
3. Support INTEGER values bigger than 2^63-1 up to 2^64-1 via BigInteger (jdbc: support -2^63 .. 2^64-1 integer type #209, sql: support UNSIGNED type tarantool#4015)
4. Support VARBINARY type (jdbc: support VARBINARY type #214, Introduce VARBINARY type in SQL frontend tarantool#4206)
5. REAL/FLOAT/DOUBLE types are supported as number aliases before v2.2
6. Support NUMBER for decimal values since 2.2.1
7. Test SCALAR against different msgpack types rather than msgbin.

next issues remain:
JDBC types conversion (appendix B)

Data Type Conversions
The recommended ResultSet getter method for each JDBC type is shown in B.6 on page B-198. This table also shows all of the possible conversions that a JDBC driver may support. The method DataBaseMetaData.supportsConvert(int fromType, int toType) returns true if the driver supports the given conversion.

It also includes ResultSet.getObject family methods, PreparedStatement.setObject family methods, and implicit conversions between types defined in Appendix B.

[Totktonada]

Nice! I think we can close this issue with PR #218 and file a new one about type conversions.

[nicktorwald]

done in commit 2cc1a09