On 11/01/2010 14:25, Tom Lane wrote:
Arnaud Betremieux<arnaud.betremi...@keyconsulting.fr> writes:
3) My use case : NOTIFY channel 'pay'||'load' (actually NOTIFY
channel '<table_name>#'||OLD.id)
4) Taken one step further : NOTIFY channel (SELECT payload FROM payloads
WHERE ...)
I'm working on a proof of concept patch to use Joachim's new notify
function to introduce case 3. I think this means going through the
planner and executor, so I might as well do case 4 as well.
It would be a lot less work to introduce a function like send_notify()
that could be invoked within a regular SELECT. Pushing a utility
statement through the planner/executor code path will do enough violence
to the system design that such a patch would probably be rejected out of
hand.
Introducing a send_notify function does sound a lot simpler and cleaner,
and I think I'll try it this way. The only thing that bothers me is the
syntax :
... DO ALSO SELECT send_notify('payload')
... DO ALSO SELECT send_notify(a) FROM b
How about a new grammar for NOTIFY <channel> a_expr, which would go
through the rewriter to be transformed as a SELECT ?
so NOTIFY (SELECT a FROM b) would become SELECT send_notify(SELECT a
FROM b) ?
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