HI, OS cache is updated and I had run the query few times with almost the same result each time.
Regards, Vishwa On Tue, Jul 14, 2020 at 6:16 PM Philip Semanchuk < phi...@americanefficient.com> wrote: > > > > On Jul 14, 2020, at 5:27 AM, Vishwa Kalyankar < > vishwakalyank...@gmail.com> wrote: > > > > Hi, > > > > I have two machines - one with 8GB RAM & 4core CPU and the other with > 64GB Ram & 24 core CPU. Both machines have the same DB (Postgres 12 + > Postgis 2.5.3). Same query is taking less time in low end machine whereas > more time in high end machine. Any thoughts on where to look? I have > tuned the db in both machines according to https://pgtune.leopard.in.ua/#/ > > > > > > Below I am pasting the output of query explain in both the machines. > > > > -bash-4.2$ psql -p 5434 > > psql (12.3) > > Type "help" for help. > > > > postgres=# \c IPDS_KSEB; > > You are now connected to database "IPDS_KSEB" as user "postgres". > > IPDS_KSEB=# explain analyze select * from > kseb_geometry_trace_with_barrier_partition(5,'kottarakara_version',437,'htline',2) > ; > > > QUERY PLAN > > > --------------------------------------------------------------------------------------------------------------------------------------------------------- > > Function Scan on kseb_geometry_trace_with_barrier_partition > (cost=0.25..10.25 rows=1000 width=169) (actual time=11626.548..11626.568 > rows=254 loops=1) > > Planning Time: 0.212 ms > > Execution Time: 11628.590 ms > > > > > > -bash-4.2$ psql -p 5422 > > psql (12.3) > > Type "help" for help. > > > > postgres=# \c IPDS_KSEB; > > You are now connected to database "IPDS_KSEB" as user "postgres". > > IPDS_KSEB=# explain analyze select * from > kseb_geometry_trace_with_barrier_partition(5,'kottarakara_version',437,'htline',2) > ; > > > QUERY PLAN > > > --------------------------------------------------------------------------------------------------------------------------------------------------------- > > Function Scan on kseb_geometry_trace_with_barrier_partition > (cost=0.25..10.25 rows=1000 width=169) (actual time=22304.425..22304.448 > rows=254 loops=1) > > Planning Time: 0.219 ms > > Execution Time: 22352.219 ms > > (3 rows) > > > > Hi Vishwa, > Is it possible that your data is in the cache on the low end machine but > not on the high end machine? There’s both the Postgres cache and the OS > disk cache to consider. You can see what’s in the Postgres cache with an > extension like pg_buffercache. I don’t know of a way to see what’s in the > OS cache; maybe others do. > > Cheers > Philip > > > > > > >
