RE: speed up a logical replica setup

Dear Shubham,

Thanks for testing our codes!

> While reviewing the v15 patches I discovered that subscription
> connection string has added a lot of options which are not required
> now:
> v15-0001
> postgres=# select subname, subconninfo from pg_subscription;
> subname | subconninfo
> -------------------------------+------------------------------------------
> pg_createsubscriber_5_1867633 | host=localhost port=5432 dbname=postgres
> (1 row)
>
>
>
> v15-0001+0002+0003
> postgres=# select subname, subconninfo from pg_subscription;
> subname |
>
> subconninfo
>
>
>
> -------------------------------+--------------------------------------------------
> ----------------------
> ----------------------------------------------------------------------------------
> ----------------------
> ----------------------------------------------------------------------------------
> ----------------------
> ------------------------------
> pg_createsubscriber_5_1895366 | user=shubham
> passfile='/home/shubham/.pgpass' channel_binding=prefer ho
> st=127.0.0.1 port=5432 sslmode=prefer sslcompression=0
> sslcertmode=allow sslsni=1 ssl_min_protocol_versi
> on=TLSv1.2 gssencmode=disable krbsrvname=postgres gssdelegation=0
> target_session_attrs=any load_balance_
> hosts=disable dbname=postgres
> (1 row)
>
>
> Here, we can see that channel_binding, sslmode, sslcertmode, sslsni,
> gssencmode, krbsrvname, etc are getting included. This does not look
> intentional, we should keep the subscription connection same as in
> v15-0001.

You should attach the script the reproducer. I suspected you used pg_basebackup
-R command for setting up the standby. In this case, it is intentional.
These settings are not caused by the pg_createsubscriber, done by pg_basebackup.
If you set primary_conninfo manually like attached, these settings would not appear.

As the first place, listed options (E.g., passfile, channel_binding, sslmode,
sslcompression, sslcertmode, etc...) were set when you connect to the database
via libpq functions. PQconninfoOptions in fe-connect.c lists parameters and
their default value.

v15-0003 reuses the primary_conninfo for subconninfo attribute. primary_conninfo
is set by pg_basebackup specified with '-R' option.
The content is built in GenerateRecoveryConfig(), which bypass parameters from
PQconninfo(). This function returns all the libpq connection parameters even if
it is set as default. So primary_conninfo looks longer.

I don't think this works wrongly. Users still can set an arbitrary connection
string as primary_conninfo. You just use longer string unintentionally.

Best Regards,
Hayato Kuroda
FUJITSU LIMITED
https://www.fujitsu.com/