[Go][Format] initial attempt at wrapping adbc for database/sql

[zeroshade]

Here's my first shot at creating the wrapper. After this I'll look into actually creating an implementation to write tests with.

However, I did come across one thing: There are Commit and Rollback methods for a connection, but there's nothing to actually begin a transaction. Nor anything specific for defining transaction options such as Isolation level or Read-Only etc.

For Go's sql package there needs to be a BeginTx method on a connection which also shouldn't require creating a new connection (ie: start a new connection with autocommit turned off?) So i'm not sure of the best way to implement this in the current framework we have.

[lidavidm]

See

arrow-adbc/c/validation/adbc_validation.c

Lines 268 to 279 in 1ca2d2d

	AdbcValidateBeginCase(adbc_context, "Connection", "enable autocommit");
	ADBCV_ASSERT_OK(&error,
	AdbcConnectionSetOption(&connection, ADBC_CONNECTION_OPTION_AUTOCOMMIT,
	ADBC_OPTION_VALUE_ENABLED, &error));
	AdbcValidateBeginCase(adbc_context, "Connection", "disable autocommit");
	ADBCV_ASSERT_OK(&error,
	AdbcConnectionSetOption(&connection, ADBC_CONNECTION_OPTION_AUTOCOMMIT,
	ADBC_OPTION_VALUE_DISABLED, &error));
	AdbcValidateBeginCase(adbc_context, "Connection", "commit/rollback succeed");
	ADBCV_ASSERT_OK(&error, AdbcConnectionCommit(&connection, &error));
	ADBCV_ASSERT_OK(&error, AdbcConnectionRollback(&connection, &error));

Disabling autocommit begins a transaction; commit/rollback also begin a transaction; enabling autocommit also runs a commit.

[zeroshade]

Gotcha, so the interfaces should allow setting options on an existing connection, not only setting options before initializing it. I'll make the adjustment.

[zeroshade]

@lidavidm Do we have any constants for setting the Isolation level of the transactions yet? If not, the golang values are:

LevelDefault
LevelReadUncommitted
LevelReadCommitted
LeveWriteCommitted
LevelRepeatableRead
LevelSnapshot
LevelSerializable
LevelLinearizable

With the documentation that if a driver does not support a given isolation level, an error may be returned. This is in addition to a ReadOnly boolean option. Should we add constants for these?

[lidavidm]

We don't, it probably makes sense to define them

[zeroshade]

@lidavidm Added them to this PR, let me know if you have any comments / issues with them. Thanks!

[lidavidm]

Interesting, so Golang has you explicitly manage transactions. DBAPI/JDBC/ODBC have "auto commit on" and you implicitly manage transactions (by disabling autocommit, then calling commit/rollback). In these APIs, readonly is a property of the connection, not the transaction. Given that the rest of the APIs are patterned after DBAPI/JDBC/ODBC, I think this would make more sense as a connection property as well.

[zeroshade]

Interesting, okay. I'll change the option to be adbc.connection.readonly instead of adbc.connection.transaction.readonly

[zeroshade]

updated, let me know if there's anything else you'd like me to modify.