Oracle turns off auto commit to drop temporary table

[mwd410]

Description

This is hopefully the final battle with Oracle to drop our temporary tables correctly, related to #16277

In my last PR, I forgot about the whole concept of auto commit. The result was the lock we acquired before the drop table was immediately released and had no effect.

Additional context and related issues

Release notes

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# Section
* Fix some things. ({issue}`issuenumber`)

[losipiuk]

this is the last operation on connection - why switch back?

[mwd410]

I think this is answered by my most recent response in the other thread

[losipiuk]

what is the motivation behind the change? Should we commit explicitly then? Or was switching auto-commit back to true just before connection is closed for that?

[losipiuk]

[losipiuk]

I see:

[losipiuk]

Please add a comment below - or just call commit() - will be more readable I think

[mwd410]

The motivation is that, because autoCommit is true when we get the Connection, the lock is immediately released because that LOCK TABLE statement is auto-committed, so the Connection has to re-acquire the lock for the DROP TABLE, so we have the same situation as we did before. Turning off auto commit holds onto that lock until after the drop table. Oracle's docs say DDL always auto-commits, but I reset autoCommit to true after the drop just in case.

[mwd410]

Oh, weird - when i typed out my reply, i only had your first comment in this thread visible to me.

I think i want to keep it as setAutoCommit(true) as it properly handles both cases: