Re: High-end PG database configuration help - Mailing list pgsql-admin

Thanks Scott,

Which of your two dbs has 2,000 connections and needs tuning, the reporting db or the web db?
Amar>> Web DB has 2000 connection. But would be great if you can also suggest tuning for reporting DB.

1: Rarely if ever is 32GB needed for shared_buffers. There's a cost to have more shared_buffers and it's pretty rare
thatanything over 1 or 2GB is needed. If you have a performance test showing you need more than a few G then yes, go
forit.
 
Amar>> reduced it to 16GB. Honestly speaking I haven’t noticed any difference in DB performance since I reduced memory
from64G to 32GB to 16GB.
 

2: You've got to get max_connections down to something reasonable. Look at pgbouncer. It's super easy to setup and will
allowyou to drop the # connections to 100 or so even for busy dbs with lots of users etc.
 
Amar>> will look into this.

Regards,
Amar

-----Original Message-----
From: Scott Marlowe [mailto:scott.marlowe@gmail.com]
Sent: 22 July 2016 17:13
To: Gupta, Amar Nath <angupta@corbus.com>
Cc: pgsql-admin@postgresql.org
Subject: Re: [ADMIN] High-end PG database configuration help

On Fri, Jul 22, 2016 at 1:57 AM, Gupta, Amar Nath <angupta@corbus.com> wrote:
> Many thanks for your reply Scott,
>
> Point#1: we have two DB servers (web app and reporting database). Web
> app does simple read and insert query + some complex queries. And
> reporting DB is used for heave queries
> Point#2: will do in next update ;)
> Point#3: I'll check for that.
> Point#4: Agreed, opening 2000 connection is not a good idea. Somehow my application is setup in this way I cannot use
pgpool,but working on it in long term.
 
> Point#5: I have setup 32GB for that.
>
> Server current configuration is:
> max_connections = 2000
> shared_buffers = 32GB
> work_mem = 128MB
> synchronous_commit = off
> effective_cache_size = 192GB
>
> rest settings are on default

Which of your two dbs has 2,000 connections and needs tuning, the reporting db or the web db?

Two points:

1: Rarely if ever is 32GB needed for shared_buffers. There's a cost to have more shared_buffers and it's pretty rare
thatanything over 1 or 2GB is needed. If you have a performance test showing you need more than a few G then yes, go
forit.
 

2: You've got to get max_connections down to something reasonable.
Look at pgbouncer. It's super easy to setup and will allow you to drop the # connections to 100 or so even for busy dbs
withlots of users etc.
 
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