Re: Autonomous Transaction (WIP)

On 09 April 2014 01:09, Rover Haas Wrote:
> I'm also pretty unconvinced that multiple PGPROCs is the right way to
> go.  First, PGPROCs have a bunch of state in them that is assumed to
> exist once per backend.  We might find pretty substantial code churn
> there if we try to go change that.

Yes you right. That is why I am not creating a separate procarray entry to
maintain autonomous transaction. Please find details in previous reply sent
today sometime back.

> Second, why do other backends
> really need to know about our ATs?  As far as I can see, if other
> backends see the AT as a subtransaction of our top-level transaction up
> until it actually commits, that ought to be just fine.  Maybe the
> backend needs to internally frob visibility rules, but that's not a
> matter for shared memory.

In order to get snapshot from other session, it will be required by other
session to access autonomous transaction and their sub-transactions.

During snapshot creation, autonomous transaction is considered as main
transaction and list of all running autonomous transaction and their sub-transaction
gets stored in snapshot data.

e.g. Suppose below processes are running with given transactions:

Proc-1: 100
Proc-2: 101, 102 (Auto Tx1), 103 (Auto Tx2), 104 (Sub-tx of Auto Tx2)
Proc-3: 105, 106 (Auto Tx2), 107 (Auto Tx2)

Suppose latest completed transaction is 108.

Then Snapshot data for autonomous transaction 107 will be as below:
Xmin:                                     100
Xmax:                                     109
Snapshot->xip[]:                          100, 101, 102, 103, 105, 106
Snapshot->subxip[]:                   104

Thanks and Regards,
Kumar Rajeev Rastogi