This should set the transaction status to in transaction

[davecramer]

https://github.com/awslabs/aws-advanced-jdbc-wrapper/blob/0b04bc682742e93c07f43c572f9a53fbf77556f6/wrapper/src/main/java/software/amazon/jdbc/wrapper/ConnectionWrapper.java#L684

[karenc-bq]

@davecramer I pushed a fix in #163

[karenc-bq]

I took the change out of #163. We will add the change in a different PR to make sure we considered all the relevant cases

[davecramer]

This should remain open until fixed

[aaron-congo]

Hi @davecramer, there are a couple workflows where setting transaction status based on setAutoCommit is problematic.

1. Switching autocommit values within a transaction. For example, you can start a transaction while autocommit is false, then, while in the same transaction, you can call setAutoCommit(true). In this case, even though autocommit is true, you are still in a transaction
2. While autocommit is on, you can execute "START TRANSACTION". Again, even though autocommit is on, the transaction status should show we are in a transaction until commit is called.

The current implementation for tracking transaction status handles these two scenarios. Admittedly, they seem like strange workflows so whether they follow recommended practices or not is another question. Regardless, since the existing drivers seem to allow this behavior, I believe we should as well.

If that makes sense, let me know and I can close this ticket. Otherwise, let me know if you have any questions. Thanks!

[davecramer]

The spec says this: which suggests otherwise.

NOTE: If this method is called during a transaction and the auto-commit mode is changed, the transaction is committed. If setAutoCommit is called and the auto-commit mode is not changed, the call is a no-op.

[aaron-congo]

Ah okay, thanks for pointing that out, I wasn't aware of that. I'll do some more investigation and get back to you

[davecramer]

So it appears that mysql does indeed do some funky stuff but PostgreSQL doesn't https://dev.mysql.com/doc/refman/8.0/en/implicit-commit.html
Mysql will actually commit the transaction in flight with another begin (most of the time)

The [BEGIN](https://dev.mysql.com/doc/refman/8.0/en/commit.html) statement differs from the use of the BEGIN keyword that starts a [BEGIN ... END](https://dev.mysql.com/doc/refman/8.0/en/begin-end.html) compound statement. The latter does not cause an implicit commit. See [Section 13.6.1, “BEGIN ... END Compound Statement”](https://dev.mysql.com/doc/refman/8.0/en/begin-end.html).

PostgreSQL will give you a warning saying there is already a transaction in process, but does not commit the transaction in flight.

[aaron-congo]

Hi Dave, could you give me more context regarding your last comment? We were discussing whether setAutoCommit should set inTransaction, but your comment seems to be referring to implicit commits. Just want to make sure I'm understanding.

Also, I did a couple tests with the mysql and postgres community drivers switching autocommit while inside a transaction. Both drivers commit the transaction when switching autocommit from false to true inside the transaction, but neither committed the transaction when switching autocommit from true to false. Should they be committing in this scenario, given the spec you mentioned?

[davecramer]

My last comment is suggesting that it appears there are real differences to the way begin is handled inside a transaction.

As for committing when going from true to false. I don't think there is a transaction that needs to be committed at that point as the are in autocommit mode and every statement is committed.