Re: 9i server performance, 5 million hits per second?

chris <chris-s_at_mailcity.com> wrote:
>Hi folks,
>
>I'm trying to get an idea on the performance of Oracle, or what might
>be required to get a performance in the region of 5 million queries
>per second, say simple select queries on an indexed table.
>
>I can foresee that there are many other variables involved here, but
>do you reckon it can handle it, any pointers on what sort of
>configuration?
>
>Sorry for the vagueness of this question, but I only need a vague
>answer!

No chance on any single machine you could buy today off-the-shelf.

Just consider memory use. You need to access a minimum of 3 blocks (index root, index leaf and data), you need to take out latches on all the buffers, then free them; at least read and calculate the hash of the SQL string and check it against the library cache, and dozens of other bits of housekeeping.

This all adds up to a few kB per query that Oracle needs to transfer from main memory to the CPU. Think about a few multiples of "a few kB" by your target of 5,000,000 queries per second:

 8kB -  40 GB/s
16kB -  80 GB/s
32kB - 160 GB/s

I'm not going to guess where in that range a single query lies.

To pick an example of a current top-end server, Compaq's marketing for the GS320 claims "Over 51GB/s aggregate internal bandwidth". Dilute that to taste for figures achievable with a real application in the field.

I've seen Oracle manage tens of thousands of queries per second; with very simple tables and queries, I'd believe a few hundred thousand to be possible.

5,000,000 lookups per second might be possible with a custom application doing hash table lookups, but I'd be very surprised if somebody could demonstrate a general purpose RDBMS doing such.

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/