Re: Patch: Implement failover on libpq connect level.

On Tue, Nov 29, 2016 at 2:19 PM, Kuntal Ghosh
<kuntalghosh(dot)2007(at)gmail(dot)com> wrote:
> On Thu, Nov 24, 2016 at 5:46 PM, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com> wrote:
>> I have taken this suggestion now renamed target_server_type to
>> target_session_attrs with possible 2 values "read-write", "any".
>> May be we could expand to "readonly" and "prefer-readonly" in next patch
>> proposal. Attaching the patch for same.
> I was doing some testing with the patch and I found some inconsistency
> in the error message.
> I've a read-only server running on port 5433 and no server on 5436 and 5438.
>
> command: bin/psql
> 'postgresql://localhost:5436,localhost:5433,localhost:5438/postgres?target_session_attrs=read-write'
>
> I get the following error message.
>
> psql: could not make a writable connection to server "localhost:5433"
> could not connect to server: Connection refused
> Is the server running on host "localhost" (::1) and accepting
> TCP/IP connections on port 5438?
> could not connect to server: Connection refused
> Is the server running on host "localhost" (127.0.0.1) and accepting
> TCP/IP connections on port 5438?
>
> It didn't show any error message for port 5436. But, if I modify the
> connection string as following:
>
> command: bin/psql
> 'postgresql://localhost:5433,localhost:5436,localhost:5438/postgres?target_session_attrs=read-write'
>
> I get the following error message:
>
> psql: could not make a writable connection to server "localhost:5433"
> could not connect to server: Connection refused
> Is the server running on host "localhost" (::1) and accepting
> TCP/IP connections on port 5436?
> could not connect to server: Connection refused
> Is the server running on host "localhost" (127.0.0.1) and accepting
> TCP/IP connections on port 5436?
> could not connect to server: Connection refused
> Is the server running on host "localhost" (::1) and accepting
> TCP/IP connections on port 5438?
> could not connect to server: Connection refused
> Is the server running on host "localhost" (127.0.0.1) and accepting
> TCP/IP connections on port 5438?

Hmm, maybe the query buffer is getting cleared someplace in there. We
might need to save/restore it.

--
Robert Haas
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