Re: Proof of concept: standalone backend with full FE/BE protocol

Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com> writes:
> On Mon, Sep 10, 2012 at 11:43 AM, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>wrote:
>> [scratches head] How's that different from the normal postmaster mode?

> As I described in later paragraphs, it'd behave like an embedded database,
> like SQLite etc., so the database will startup and shutdown with the
> application, and provide other advantages we're currently trying to
> provide, like zero-maintenance. But it will not mandate that only one
> application talk to it at a time, and allow as many applications as it
> would in postmaster mode. So the database would be online as long as any
> application is connected to it, and it will shutdown when the last
> application disconnects.

I am having a hard time getting excited about that. To me it sounds
like it's a regular postmaster, except with a response-time problem for
connections that occur when there had been no active client before.

The point of the proposal that I am making is to have a simple,
low-maintenance solution for people who need a single-application
database. A compromise somewhere in the middle isn't likely to be an
improvement for anybody. For instance, if you want to have additional
connections, you open up a whole collection of communication and
authentication issues, which potential users of a single-application
database don't want to cope with.

> As being implemented right now, there's very little difference between
> --single and --child modes. I guess I am asking for a --child mode
> implementation that is closer to a postmaster than --single.

There are good reasons for wanting something that is closer to --single:
pg_upgrade being one, and having a friendlier user interface for
disaster recovery in --single mode being another. In these cases, you
not only don't need the capability for additional applications to
connect, it is actually important that it's impossible for them to do
so.

regards, tom lane