On 6/25/12 10:23 AM, Kevin Grittner wrote:
> Craig James <cjames@emolecules.com> wrote:
>
>> It claims to be "the world's fastest database."
>
>> [link where they boast of 80,000 tps read-only]
>
> 20,000 tps? Didn't we hit well over 300,000 tps in read-only
> benchmarks of PostgreSQL with some of the 9.2 performance
> enhancements?
Yes. The dirty truth is that there's nothing special, performance-wise,
about an "in memory" database except that it doesn't write to disk (or
protect your data from power-out).
In the early 00's people thought that you could build a database in some
fundamentally different way if you started with the tenet that it was
100% in memory. Hence RethinkDB, MySQL InMemory Tabletype, etc.
As it turns out, that doesn't change anything; you still need data
pages, indexes, sort routines, etc. etc. "Disk" databases don't operate
off disk; they get copied to memory, so they're already effectively "in
memory".
BTW, VoltDB's innovation is not being "in memory" (it can spill to
disk), but rather their innovative transactional clustering approach.
The new non-relational databases are "fast" on poor hardware (Amazon,
developer laptops) by cutting features and optimizing for poor (but
common) access patterns. Not by being "in memory", which is just a
side effect of not having spill-to-disk code.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com