Hi
2014-08-09 10:20 GMT+02:00 Guillaume Lelarge <guilla...@lelarge.info>: > Hi, > > Le 9 août 2014 05:57, "Ramirez, Danilo" <danilo.rami...@hmhco.com> a > écrit : > > > > Thanks to all for the great info. We are new to postgresql and this > discussion has both instructed us and increased our respect for the > database and the community. > > > > I am seeing a behavior that I don’t understand and hopefully you guys > can clear it up. > > > > I am using AWS postgresql db.m3.2xlarge and using pgadmin III 1.18 > comparing against AWS oracle on db.m3.2xlarge using sql developer and TOAD. > > > > I am running a query with 30 tables in the from clause, getting 137 > columns back (this is our most basic query, they get a lot more more > complex). It returns back 4800 rows. > > > > In oracle 1st run takes 3.92 seconds, 2nd .38 seconds. Scrolling to end > takes and extra 1.5 seconds for total of 5.5. > > > > Using pgadmin, I run the query. Looking at the lower right hand I can > see the time going up. It stops at 8200 ms or close to it every time, then > it takes an extra 6 seconds before it displays the rows on the screen. > 2nd, 3rd, etc. runs all take about same amount of time 8 sec plus 6 sec > > > > I then changed it to return only 1 column back. In oracle/sqldeveloper > identical behavior as before, same time. In postgresql it now goes down to > 1.8 seconds for 1st, 2nd, etc. runs. > > > > I then change it so that I am asking for the sum of 1 column. In oracle > time goes down to .2 seconds and postgresql now goes down to .2 seconds > also. > > > > I then change it back to get the full result set and behavior goes back > to original, oracle .38 since its cached, postgresql 8 seconds. > > > > Are you sure this is postgresql 8 seconds? I'd believe this is more > something like postgresql something really low and PgAdmin around 8 seconds > displaying it. What I mean is, PgAdmin uses really slow UI components and > the time it shows is the time to execute the query and display the data. > IOW, you shouldn't use it to benchmark. You should better use psql. Or, > much better, you should set log_min_duration_statement to 0 and see exactly > how much time postgresql needs to execute it. > yes, try to eliminate a impact of PgAdmin for this purpose use psql \timing \o /dev/null SELECT ... -- your query Regards Pavel p.s. you can send a plans of slow and fast variants.
