Re: An issue in JDBC replication API

Hi Abbas,

Thanks for this I seem to recall something about this.

Dave Cramer
www.postgres.rocks

On Fri, 19 Jun 2020 at 16:40, Abbas Butt <abbas(dot)butt(at)enterprisedb(dot)com>
wrote:

> Hi,
> I have found that the JDBC replication API does not handle the keep alive
> messages sent by the server correctly.
> A replication client cannot ignore even a single keep alive message from
> the server and it must respond to it.
> If it does not the server will stop WAL sender with the following error:
> LOG: terminating walsender process due to replication timeout
> LOG: disconnection: session time: 0:02:00.173 user=replicant database=edb
> host=127.0.0.1 port=57900
>
> and this is exactly what is happening when I use JDBC replication API.
> The JDBC driver is ignoring the server's keep alive messages and hence the
> server stops the WAL sender and drops the connection.
>
> Attached please find a sample program that I have mostly copied from the
> documentation available here
>
> https://jdbc.postgresql.org/documentation/head/replication.html#logical-replication
>
> When we run this program and do not do any activity on the database server
> (I have tested with server version 12 and JDBC 42.2.14), after some time (wal_sender_timeout/2
> seconds to be precise) the server stops the WAL sender process and drops
> the connection.
> To use the program follow these steps:
>
> Issue the following commands to the database server:
> ./createuser --superuser --replication -h 127.0.0.1 -p 7777 -U postgres
> replicant
> select pg_drop_replication_slot('radium');
> CREATE TABLE numbers(a int PRIMARY KEY, b varchar(255));
> GRANT SELECT on numbers to replicant;
> INSERT INTO numbers VALUES(10, 'ten'),(20,'twenty'),(30,'thirty');
> CREATE PUBLICATION barium for TABLE numbers;
>
> To run the program use the following commands:
> mvn clean
> mvn package
> java -cp
> target/Lithium-1.0-SNAPSHOT.jar:/home/abbas/tmp/postgresql-42.2.14.jar
> com.edb.App
>
> If my analysis is correct, can we please have this issue fixed in the
> driver?
>
> Best Regards
>
> --
> --
> *Abbas*
> Architect
>
> Ph: 92.334.5100153
> Skype ID: gabbasb
> www.enterprisedb.co <http://www.enterprisedb.com/>m
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