From: Tom Lane <tgl@sss.pgh.pa.us>
To: Shrikant Bhende <shrikantpostgresql@gmail.com>
Cc: pgsql-admin@lists.postgresql.org
Subject: Re: Slow running query
Date: Wed, 11 Dec 2019 10:32:49 -0500
Message-ID: <14517.1576078369@sss.pgh.pa.us> (raw)
In-Reply-To: <CAMTQpJD-DvtO=1XL-VC85iFRDTSYqz-b_Ha6L1dif=4ZO=hbwg@mail.gmail.com>
References: <CAMTQpJD-DvtO=1XL-VC85iFRDTSYqz-b_Ha6L1dif=4ZO=hbwg@mail.gmail.com>
Shrikant Bhende <shrikantpostgresql@gmail.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
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Subject: Re: Slow running query
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