Re: Hardware Configuration and other Stuff - Mailing list pgsql-performance

Hi,

On 18.3.2015 20:07, Vivekanand Joshi wrote:
> Hi Team,
>
> I don't know under which section does this question comes, so I am
> posting this question to both Admin and performance mailing list.
> Apologies in advance.

Let's keep this in pgsql-performance.

>
> Objective:
>
> We are planning to use PostgreSQL instead of Netezza for our data
> warehouse as well as database solutions. Right now, we have all our
> clients in one Netezza box. What we are thinking of migrating our
> clients to dedicated PostgreSQL for each of them. We will start with
> one of the client. If it works successfully, we will be migrating all
> the clients one by one. The objective is to get a better performance
> than our existing solution. We are hopeful of that mainly because of
> two reasons. Firstly, we will have a dedicated server for each of the
> client with good hardware instead of having one server with all the
> clients on that. Secondly, we can spend on hardware much easily than
> spending on a proprietary appliance.
>

OK.

> I am hoping this community can help us to know that what would be the
> good infrastructure/hardware that can help us in achieving our goal.
>
> Here are few of the statistics which might act as a starting point.
>
> Availability: High (24*7).
>
> User Data : 700 GB which will increase to 1.5 TB in next 2-3 years.

How do you measure the amount of data? Is that the amount of data before
loading, size of the database, or what?

Also, is this a single client (thus placed on a single box), or multiple
clients?

> Number of User Databases : 2 (One is the main database, other is
> used only for working tables where tables gets deleted in every 48
> hours)

You mentioned 700GB of data - is that just the main database, or both
databases?

>
> Number of tables : 200 (in the main database), (2000-3000 in working
> database)
>
> Size of top 5 biggest tables : 20-40 GB
>
> No of users concurrently accessing the system : 5-6 with write
> access. 10 with read access.
>
> No of User Queries running on the system in a day : ~80K
>
> Read-only Queries (Select): ~60K
>
> Write queries: ~20K
>
> Data Import Queries: ~1K
>
> Typical Business Day : 18-20 hours.

So is this a typical "batch" environment when you do the loads at night,
but no during loads? That might be possible with clients on dedicated
boxes and would allow various optimizations.

>
> I can pass on few complex queries to let you guys know what are we
> doing.
>
> Here are few questions:
>
> 1.) I don't need a load balancing solution. It must be high availability
> server and I can work with asynchronous replication. The most important
> thing here would be recovery should be as fast as possible.
>
> What approach would you recommend?

Streaming replication. I would probably start with sync replication.

> 2.) Recommendations on indexes, WAL, table spaces. I am not asking
> about on which key I need to make indexes, but an high level approach
> about how to keep them? This might come out as a weird question to
> many but please excuse me for being a novice.

Not sure what exactly are you looking for - there's a lot of things, and
many of them depend on what hardware you plan to use.

The simplest indexing strategy is to design them along with the schema,
and evaluate them on queries (collect slow queries -> create suitable
indexes -> repeat).

>
> 3.) What would be the ideal hardware configuration for this
> requirement? I know there is not a one-stop answer for this, but
> let's take it is a starting point. We can come to a proper conclusion
> after a discussion.

This is very complex question, to be honest. I assume you're looking for
regular servers, in that case a good server with not that many CPUs
(say, 32 cores seems to be enough for your workload), plenty of RAM and
good disk system to handle the load would be a good start.

> What are the best on-line resources/books which can tell us about
> the hardware requirements?

I'd say these two books would be helpful:

(1)
https://www.packtpub.com/big-data-and-business-intelligence/postgresql-9-high-availability-cookbook

   - explains capacity planning etc.

(2)
https://www.packtpub.com/big-data-and-business-intelligence/postgresql-90-high-performance

   - a good book about PostgreSQL performance tuning

regards

--
Tomas Vondra                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services