feat: add tx methods to IDB (#587)

[isgj]

Updated IDB interface with 2 methods

BeginTx(ctx context.Context, opts *sql.TxOptions) (Tx, error)
RunInTx(ctx context.Context, opts *sql.TxOptions, f func(ctx context.Context, tx Tx) error) error

When creating a savepoint the opts are ignored.
Currently the transaction will not use the name but we can store something like TX_{random} same format as for savepoint. Then we can also emit the name with the hooks so logging libraries can show if a query is being executed as part of a transaction or savepoint.

[vmihailenco]

Let's not add a dependency on uuid just to generate a random string.

    b := make([]byte, 16)
    rand.Read(b)

[isgj]

I used crypto/rand but I think also math/rand is an option as it is safe for concurrent usage (for this usage pseudo random is fine). Maybe we can check which is faster but that will be one word change.

[vmihailenco]

Thanks, crypto/rand is fine I guess.

[vmihailenco]

This looks pretty good. Could you add a test for savepoints in https://github.com/uptrace/bun/blob/master/internal/dbtest/db_test.go#L273?

[isgj]

mssql has a different syntax https://docs.microsoft.com/en-us/sql/t-sql/language-elements/save-transaction-transact-sql?view=sql-server-ver16

How are these cases handled when different sql should be generated?

[vmihailenco]

How are these cases handled when different sql should be generated?

You can add a feature flag for mssql here and use it like this

[vmihailenco]

Excellent, thank you 👍