Re: [EXTERNAL] Re: Support load balancing in libpq

Attached an updated patch which should address your feedback and
I updated the commit message.

> I wonder whether making the parameter a boolean will paint us into a
> corner

I made it a string option, just like target_session_attrs. I'm pretty sure a 
round-robin load balancing policy could be implemented in the future
given certain constraints, like connections being made within the same
process. I adjusted the docs accordingly.

> > +typedef struct
> > +{
> > +	int			family;
> > +	SockAddr	addr;
> > +}			AddrInfo;
>
> That last line looks weirdly indented compared to SockAddr; in the
> struct above.

Yes I agree, but for some reason pgindent really badly wants it formatted
that way. I now undid the changes made by pgindent manually.

> I wonder whether this needs to be documented if it is mostly a
> development/testing parameter?

I also wasn't sure whether it should be documented or not. I'm fine with
either, I'll leave it in for now and let a committer decide if it's wanted or not.

> A bit unclear why you put the variables at this point in the list, but
> the list doesn't seem to be ordered strictly anyway; still, maybe they
> would fit best at the bottom below target_session_attrs?

Good point, I added them after target_session_attrs now and also moved
docs/parsing accordingly. This makes conceptually to me as well, since
target_session_attrs and load_balance_hosts have some interesting
sense contextually too.

P.S. I also attached the same pgindent run patch that I added in
https://www.postgresql.org/message-id/flat/AM5PR83MB0178D3B31CA1B6EC4A8ECC42F7529@AM5PR83MB0178.EURPRD83.prod.outlook.com