desmodemone wrote: > As I tested and saw until now, the keep alive functions as follow [if I understand correctly and it's > not a bug] : > > When a connection it's in idle state or in idle in transaction, if the connection with client it's > broken for a number of keep alive, the backend will be terminated. > > > By the way if this could be ok in an OLTP enviroment, because the average time of a query is << the > time of keep alive, in a DWH enviroment could be a problem. > > Imagine your application server, where there is an ETL, will go down for 1 minute and your > transactions are still running on the DWH database, that transactions could run for hours before the > > keep alive will terminate them, because they are in transaction state and not idle or idle in > transaction.
TCP keepalive will also terminate a session that is currently stuck in a long running SQL query if the client end dies.
I think that your problem is that you mix up different meanings of "idle".
In PostgreSQL, a connection is idle (or idle in transaction) if processing of the last command is finished and the server is waiting for the next command from the client.
In TCP, a connection is idle if there is no network traffic.
Yours, Laurenz Albe
Hello Laurenz,
so I have a strange behavior on some test servers.
I am using Centos 6.4 and I set up the tcp keep alive kernel parameter very low to see the effects [the postgresql.conf parameter have 0 value so use the OS value] :
then I run a long query from a remote client and I kill that "psql client" . By the way, even even if after long time, the query remains alive,
until it finishes and it returns error because could not return the row to the client.
If I do the same with an update, it's the same except become idle in transaction and only after then it's killed .
So, if " TCP keepalive will also terminate a session that is currently stuck in a long running SQL query if the client end dies." , what is wrong on the setup ? Could someone try the tcp keep alive or explain why is not working as expected ?