Re: autonomous transactions - Mailing list pgsql-hackers

From Greg Stark
Subject Re: autonomous transactions
Date
Msg-id CAM-w4HNniRP_bgPyVqj0LTm1YCR+CiL-vgWxogRe55JvJzPB8g@mail.gmail.com
Whole thread Raw
In response to autonomous transactions  (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>)
Responses Re: autonomous transactions  (Craig Ringer <craig@2ndquadrant.com>)
Re: autonomous transactions  (Serge Rielau <serge@rielau.com>)
Re: autonomous transactions  ("Constantin S. Pan" <kvapen@gmail.com>)
Re: autonomous transactions  (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>)
List pgsql-hackers
On Wed, Aug 31, 2016 at 2:50 AM, Peter Eisentraut
<peter.eisentraut@2ndquadrant.com> wrote:
> - A API interface to open a "connection" to a background worker, run
> queries, get results: AutonomousSessionStart(), AutonomousSessionEnd(),
> AutonomousSessionExecute(), etc.  The communication happens using the
> client/server protocol.
>


I'm surprised by the background worker. I had envisioned autonomous
transactions being implemented by allowing a process to reserve a
second entry in PGPROC with the same pid. Or perhaps save its existing
information in a separate pgproc slot (or stack of slots) and
restoring it after the autonomous transaction commits.

Using a background worker mean that the autonomous transaction can't
access any state from the process memory. Parameters in plpgsql are a
symptom of this but I suspect there will be others. What happens if a
statement timeout occurs during an autonomous transaction? What
happens if you use a pl language in the autonomous transaction and if
it tries to use non-transactional information such as prepared
statements?


-- 
greg



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