Re: speed up a logical replica setup

On Wed, Mar 13, 2024, at 10:09 AM, Shlok Kyal wrote:
> Added a top-up patch v28-0005 to fix this issue.
> I am not changing the version as v28-0001 to v28-0004 is the same as above.

Thanks for your review!

I'm posting a new patch (v29) that merges the previous patches (v28-0002 and
v28-0003). I applied the fix provided by Hayato [1]. It was an oversight during
a rebase. I also included the patch proposed by Shlok [2] that stops the target
server on error if it is running.

Tomas suggested in [3] that maybe the PID should be replaced with something
else that has more entropy. Instead of PID, it uses a random number for
replication slot and subscription. There is also a concern about converting
multiple standbys that will have the same publication name. It added the same
random number to the publication name so it doesn't fail because the
publication already exists. Documentation was changed based on Tomas feedback.

The user name was always included in the subscriber connection string. Let's
have the libpq to choose it. While on it, a new routine (get_sub_conninfo)
contains the code to build the subscriber connection string.

As I said in [4], there wasn't a way to inform a different configuration file.
If your cluster has a postgresql.conf outside PGDATA, when pg_createsubscriber
starts the server it will fail. The new --config-file option let you inform the
postgresql.conf location and the server is started just fine.

I also did some changes in the start_standby_server routine. I replaced the
strcat and snprintf with appendPQExpBuffer that has been used to store the
pg_ctl command.

[1] https://www.postgresql.org/message-id/TYCPR01MB12077FD21BB186C5A685C0BF3F52A2%40TYCPR01MB12077.jpnprd01.prod.outlook.com
[2] https://www.postgresql.org/message-id/CANhcyEW6-dH28gLbFc5XpDTJ6JPizU%2Bt5g-aKUWJBf5W_Zriqw%40mail.gmail.com
[3] https://www.postgresql.org/message-id/6423dfeb-a729-45d3-b71e-7bf1b3adb0c9%40enterprisedb.com
[4] https://www.postgresql.org/message-id/d898faad-f6d7-4b0d-b816-b9dcdf490685%40app.fastmail.com

--
Euler Taveira
EDB https://www.enterprisedb.com/