Re: request for database identifier in the startup packet

Dave Cramer

On Thu, 9 May 2024 at 12:22, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Thu, May 9, 2024 at 8:06 AM Dave Cramer <davecramer(at)gmail(dot)com> wrote:
> > The JDBC driver is currently keeping a per connection cache of types in
> the driver. We are seeing cases where the number of columns is quite high.
> In one case Prevent fetchFieldMetaData() from being run when unnecessary. ·
> Issue #3241 · pgjdbc/pgjdbc (github.com) 2.6 Million columns.
> >
> > If we knew that we were connecting to the same database we could use a
> single cache across connections.
> >
> > I think we would require a server/database identifier in the startup
> message.
>
> I understand the desire to share the cache, but not why that would
> require any kind of change to the wire protocol.
>
> The server identity is actually useful for many things such as knowing
which instance of a cluster you are connected to.
For the cache however we can't use the IP address to determine which server
we are connected to as we could be connected to a pooler.
Knowing exactly which server/database makes it relatively easy to have a
common cache across connections. Getting that in the startup message seems
like a good place

Dave