Re: idle_in_transaction_timeout

Abhijit Menon-Sen <ams(at)2ndquadrant(dot)com> wrote:
> At 2014-06-19 10:58:34 +0200, pavel(dot)stehule(at)gmail(dot)com wrote:

>> pgbouncer has idle_transaction_timeout defined some years
>> without any problems, so we can take this design
>>
>> idle_transaction_timeout
>
> Let's steal the name too. :-)
>
> (I didn't realise there was precedent in pgbouncer, but given
> that the name is in use already, it'll be less confusing to use
> that name for Postgres as well.)

I'm not sure whether using the same name as pgbouncer for the same
functionality makes it less confusing or might lead to confusion
about which layer is disconnecting the client.  I'm leaning toward
using the same name, but I'm really not sure.  Does anyone else
want to offer an opinion?

Somehow I had thought that pg_stat_activity didn't show a
connection as "idle in transaction" as soon as BEGIN was run -- I
thought some subsequent statement was needed to put it into that
state; but I see that I was wrong about that.  As long as BEGIN
causes a connection to show as "idle in transaction" I think the
BEGIN should start the clock on this timeout, based on POLA.  It
wouldn't bother me to see us distinguish among early transaction
states, but I'm not sure whether it's really worth the effort.  We
couldn't base it just on whether the transaction has acquired a
snapshot, since it is not unusual for explicit LOCK statements at
the front of the transaction to run before a snapshot is acquired,
and we would want to terminate a transaction sitting idle and
holding locks.

Also, it seems like most are ok with the FATAL approach (as in v1
of this patch).  Does anyone want to make an argument against
proceeding with that, in light of discussion so far?

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company