How to add guc options on startup message?

[ttqs5]

In ProcessStartupPacket (postmaster.c) , all unknown param was assumed as a GUC option.
But in getParametersForStartup(ConnectionFactoryImpl.java),It seem that it never add addition custom params to startupMessage.

What is the recommend way to init guc options for a connection?

// postmaster.c
// ProcessStartupPacket
while (offset < len)
{
...
   if (strcmp(nameptr, "XXXX") == 0)
    {
    }
    ... 
    else
			{
				/* Assume it's a generic GUC option */
				port->guc_options = lappend(port->guc_options,
											pstrdup(nameptr));
				port->guc_options = lappend(port->guc_options,
											pstrdup(valptr));
			}

[davecramer]

I'm not sure what showing us the C code for postmaster has to do with JDBC ? We don't do many things the same as the postmaster code.

[ttqs5]

Is it ok that the driver support this feature?
I can make a commit.

If not, why?
Less is better or it`s a bad design?

[davecramer]

I guess I would wonder why you want to do this? What are you trying to solve?

[ttqs5]

for example,
jdbc:postgresql://xxx/db?idle_in_transaction_session_timeout=60

config guc init value for session

[davecramer]

you can always set it in the code. SET idle_in_transaction_session_timeout to 60

[ttqs5]

Change config is much easier than change code.
Some BI tool even cannot do that , only if set the db-level guc value.

[davecramer]

As @sehrope mentions below this is already possible using OPTIONS config

[ttqs5]

Thanks for your patient reply!

[sehrope]

This is already implemented. You can add arbitrary backend initialization parameters via the OPTIONS connection property:

https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/PGProperty.java#L354-L361

Check out the "options" connection parameter for details on usage: https://jdbc.postgresql.org/documentation/head/connect.html#connection-parameters

[ttqs5]

It works!!! Thank you!