Re^6: Preventing database handles from going stale

It's not timing out in a matter of seconds, it just appears that DBD::Pg->ping is not sufficient as a keepalive. I'd estimate that I'm seeing a 5 minute timeout, but I haven't done any testing specifically aimed at verifying that.

The race condition I'm talking about (assuming a 5 minute timeout) is that the ping could run 4 minutes 59.999 seconds after the last query (while everything is still fine), the connection times out at 5 minutes, and then the next query (tries to) run at 5 minutes and 0.001 seconds after the previous one. eval is indeed the only way to catch that scenario and recover from it, but an ounce of prevention and all that.

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Re^7: Preventing database handles from going stale by kyle (Abbot) on Feb 05, 2007 at 18:28 UTC
I think `ping` is implemented as a query. I sometimes see "`SELECT 'DBD::Pg ping test'`" in `pg_stat_activity`, and I can't imagine that's anything else.	[reply] [d/l] [select]
Re^8: Preventing database handles from going stale by EvanK (Chaplain) on Feb 05, 2007 at 18:46 UTC
It is, I just took a peek at the source code for it, and it does a SELECT (dbd_db_ping(dbh) in dbdimp.c). I don't know why that wouldn't be enough to keep the connection alive though...Perhaps the query needs to interact with an existing table to keep the connection alive? __________ The trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it. - Terry Pratchett	[reply]