Tom Lane wrote:
Mark Morgan Lloyd <markMLl.pgsql-general@xxxxxxxxxxxxxxx> writes:
Do any special precautions need to be taken when PQNotifies is being
called, to make sure that nothing else is referencing the handle?
It's pretty much the same as any other operation on a PGconn: if there
could be more than one thread touching the connection object
concurrently, you'd be well advised to add some application-level
locking.
http://www.postgresql.org/docs/9.2/static/libpq-threading.html
The lack of any such locking inside libpq is partly historical, and
partly because in many practical situations you'll need application-side
locks anyway to protect application data structures associated with the
connection.
Thanks, Tom. I'm fairly happy with the ways I've used it so far, but I'm
just trying to think ahead for the future.
In the case of Delphi/Lazarus, where you can have multiple queries on
top of the same connection object, my experience so far is that using
the connection object's handle is safe. But I think that to be
absolutely confident of that I need to do some tracing, and find out
under what circumstance calls are being issued directly against that
handle rather than it just being a placeholder for authentication etc.
--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk
[Opinions above are the author's, not those of his employers or colleagues]
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