Re: Processor speed relative to postgres transactions per second

On Mar 29, 2010, at 9:42 AM, Chris Barnes wrote:

>
> We have two camps that think that the speed of cpu processors is/aren't relative to the number of transactions that postgres that can performed per second.
>
> I am of the opinion that is we throw the faster processors at the database machine, there will be better performance.
>
> Just like faster drives and controllers, there must be some improvement over the other processor.
>
> Is there anything to support this, a document or someone's personal experience?
>

There will always be a bottleneck. If your query speed is limited by the time it takes for the drives to seek, then you can throw as much CPU at the problem as you like and nothing will change. If your query speed is limited by the time it takes to read data from memory, a faster CPU will only help if it has a faster memory bus. If you're limited by complex or slow functions in the database then a faster CPU is what you need.

For larger databases, IO speed is the bottleneck more often than not. In those cases throwing memory, better disk controllers and faster / more drives at them will improve things. More CPU will not.

Also, the price/speed curve for CPUs is not pretty at the higher end. You can get a lot of RAM or disk for the price difference between the fastest and next fastest CPU for any given system.

Cheers,
Steve