Re: Slow running query

Shrikant Bhende <shrikantpostgresql(at)gmail(dot)com> writes:
> Below is the query which is running very slow, can anyone suggest any
> improvement for the same to make it faster.

Not when you haven't given us any supporting data :-(. There's some
advice about how to ask useful performance questions here:

https://wiki.postgresql.org/wiki/Slow_Query_Questions

However, just scanning your EXPLAIN output, it seems that the bulk
of the time is being spent inside two user-defined functions:

> -> Function Scan on get_num_connections f (cost=0.25..10.25 rows=1000 width=24) (actual time=22331.461..22331.479 rows=263 loops=1)
...
> -> Function Scan on get_num_proprietary f_1 (cost=0.25..10.25 rows=1000 width=24) (actual time=4052.081..4052.085 rows=26 loops=1)
...
> Planning time: 18.362 ms
> Execution time: 33944.679 ms

ie, 26 of the 34 seconds are being spent there. You're not going to be
able to move the needle very far unless you can make those a lot cheaper.

I notice that the first thing the plan does with these is FULL JOIN them
to each other, which seems suspiciously like a performance anti-pattern.

regards, tom lane