[Lazarus] Postgresql listen/notify

Mark Morgan Lloyd markMLl.lazarus at telemetry.co.uk
Tue May 8 10:01:45 CEST 2012

Leonardo M. Ramé wrote:
> Hi, does sql-db allows to capture PostgreSql notify events?. If yes,
> how?.

Indirectly. You have to set it up using the TPQConnection.Handle since 
this has long-term persistence, and have to make direct API calls *not* 
ExecuteDirect() since that uses a temporary handle. It works, but is 
sensitive to transient network failures etc.: the server end can forget, 
so it's wise to have a fallback mechanism.

I don't know whether it should be treated as a candidate for an 
extension to the sql-db API, since as far as I know there's something 
comparable (implemented very differently) on Firebird but nothing else.

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

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