Re: subtransactions -- storage manager

On Sun, 2004-04-25 at 19:06, Alvaro Herrera wrote:
> Hackers,
>
> This patch adds subtransaction support into the storage manager.  Files
> created or dropped inside a subtransaction are correctly dealt with at
> subtransaction commit or abort.

> - pg_clog/pg_subtrans.  Need a solution.
>
>
> PS: somehow I managed to get tired of the phrase "nested transactions"
> and I'm using the term "subtransactions" instead.  In my head they are
> the same thing ...

Impressive.

As you're aware, our current work overlaps.
pg_clog doesn't seem like the place to record subtransactions, though
maybe it is... could we not give subtransactions a txnid just as with
flat transactions? That way we can record everything in pg_clog AND
recovery will work without further modification - as long as the failure
of a top level transaction causes failure of every subtransaction EVEN
if the subtrans originally committed.

If you add pg_subtrans, you will need to make recovery work all over
again...really, you don't want to be doing that, do you?

I also have other questions....
Forgive my lack of attention: I want SAVEPOINTs, not subtransactions...
how do we do those?

My last focus on this was to do with SQL handling of transactional
rollback characteristics on error. PostgreSQL performs rollback on
complete txn when error occurs, rather than allowing statement level
abort and then retry...this was characterised as requiring "nested
transactions"...are your aware of this...is it on your roadmap.

Best Regards, Simon Riggs