Re: One transaction and several processes - Mailing list pgsql-hackers

From David G. Johnston
Subject Re: One transaction and several processes
Date
Msg-id CAKFQuwY+q05xV2zCto3QJXHNZZfnQ0D0swV9m6GApA9q-cA0RQ@mail.gmail.com
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In response to One transaction and several processes  (Valery Kuzmin <valerij.kuzmin@gmail.com>)
List pgsql-hackers
On Wed, Jul 18, 2018 at 8:31 AM, Valery Kuzmin <valerij.kuzmin@gmail.com> wrote:
Hi,

Can multiple processes participate in a single transaction's execution?
I need to do the following actions sequence:
1. Calling service begins transaction. At this step transaction
manager generate new XID.
2. Calling service updates some data.
3. Need to detach a transaction from a service context before other
service is called.
4. Called service resume transaction using XID.
5. Called service updates its data.
6. Calling service gets control, resume transaction using XID and does commit.
How can the third and fourth step be implemented?

​Your original pgsql-general post was the right place for this but I see it got no response​...

Basically no, if you need multiple service processes to share a session you would need to share the persistent database connection between them at a higher level (i.e., outside the database).  IOW, the physical connection needs to be shared, not an XID.

Depending on the specifics of this orchestration two-phase commit might provide some useful capabilities but its considerably harder to setup reliably.

David J.

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