[Pgpool-general] PgPool and sequences

[Pascal Cohen]

Pascal Cohen wrote:
> Hello, I have read in the documentation that there is no guarantee that 
> sequence may have the same value on all servers.
>
> This is not perhaps not very probable (theoretical) but could such a 
> following situation occur:
>
> I have two servers replicated and I want to add in a users table (id, 
> name) with a sequence users_seq, two users A and B:
>
> First connection sends to PgPool: INSERT INTO USERS VALUES 
> (next_val('users_seq'),'A');  -- ReqA
> At the same time a second connection sends to PgPool: INSERT INTO USERS 
> VALUES (next_val('users_seq'),'B'); -- ReqB
>
> Could we have something like:
> - On Server 1:
> 1 A
> 2 B
> - On server 2:
> 1 B
> 2 A
>
> I mean updates are not sent in the same order to all servers for any 
> reason (several CPUs on server handling the request slower, or anything 
> else). Is that possible ?
>
> Thanks
>
> Pascal
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>   
maybe I should have said PgPool-II instead of PgPool whenever it makes a 
difference on that subject.