Hi,
On Wed, Jun 29, 2016 at 6:29 PM, Craig Ringer <cr...@2ndquadrant.com> wrote: > On 29 June 2016 at 18:47, Sachin Kotwal <kotsac...@gmail.com> wrote: > > >> I am testing pgbench with more than 100 connections. >> also set max_connection in postgresql.conf more than 100. >> >> Initially pgbench tries to scale nearby 150 but later it come down to 100 >> connections and stable there. >> >> It this limitation of pgbench? or bug? or i am doing it wrong way? >> > > What makes you think this is a pgbench limitation? > As I mentioned when I tried same thing with sysbench It can give me 200+ concurrent connection with same method and same machine. > It sounds like you're benchmarking the client and server on the same > system. Couldn't this be a limitation of the backend PostgreSQL server? > > I think having client and server on same server should not be problem. As i can do this with different benchmarking tool It should not be limitation of backend PostgreSQL server. > It also sounds like your method of counting concurrent connections is > probably flawed. You're not allowing for setup and teardown time; if you > want over 200 connections really running at very high rates of connection > and disconnection you'll probably need to raise max_connections a bit to > allow for the ones that're starting up or tearing down at any given time. > > May be. Please let me know how I can count concurrent connection in this case. There should not be connection and disconnection because I am not using -C option of pgbench which cause connection and disconnection for each query. If I set max_connection of postgresql.conf to 200 and testing with -c 150 . This should work fine, but it is not. > Really, though, why would you want to do this? I can measure my car's > speed falling off a cliff, but that's not a very interesting benchmark for > a car. I can't imagine any sane use of the database this way, with > incredibly rapid setup and teardown of lots of connections. Look into > connection pooling, either client side or in a proxy like pgbouncer. > > > I am testing one scenario of multiple coordinator with help of postgres_fdw to enhance connection ability of postgres without any connection pooling . Setup might be difficult to explain here but will explain if required. can you test simply 100 scale database size with pgbench and run pgbench with 200+ connection of small virtual box to see same observation ? Please let me know if I can help to know to reproduce this problem. > -- > Craig Ringer http://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Training & Services > -- Thanks and Regards, Sachin Kotwal
