Re: Deadlocks and transactions

On 21 March 2018 at 13:10, JORGE MALDONADO <jorgemal1960(at)gmail(dot)com> wrote:
> Let´s suppose the following scenario.
> * User 1 has already loaded a web page and clicks a button that triggers a
> transaction that includes 2 tables.
> * User 2 loads the same page and SELECTs data from the 2 tables currently in
> the transaction generated by User 1. User 2 does not trigger a transaction
> because he/she only gets data from the DB.
>
> Is there any issue/problem for User 2?

There's no deadlock risk between a read and a write transaction. This
is mentioned in the 2nd paragraph in
https://www.postgresql.org/docs/10/static/mvcc-intro.html

That might be interesting for you to read as it explains in a bit of
detail how concurrency is handled in PostgreSQL.

> (Is it correct to reply-to-all when posting back to a question?)

Yes. It's also our preference that you don't top post in replies. We
generally use the interleaved style described in
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services