On May 3, 2011, at 5:39 PM, Greg Smith wrote:
> I've also seen over a 20:1 speedup over PostgreSQL by using Greenplum's free Community Edition server, in situations
whereits column store + compression features work well on the data set. That's easiest with an append-only workload,
andthe data set needs to fit within the constraints where indexes on compressed data are useful. But if you fit the
useprofile it's good at, you end up with considerable ability to trade-off using more CPU resources to speed up
queries. It effectively increases the amount of data that can be cached in RAM by a large multiple, and in the EC2
context(where any access to disk is very slow) it can be quite valuable.
FWIW, EnterpriseDB's "InfiniCache" provides the same caching benefit. The way that works is when PG goes to evict a
pagefrom shared buffers that page gets compressed and stuffed into a memcache cluster. When PG determines that a given
pageisn't in shared buffers it will then check that memcache cluster before reading the page from disk. This allows you
tocache amounts of data that far exceed the amount of memory you could put in a physical server.
--
Jim C. Nasby, Database Architect jim@nasby.net
512.569.9461 (cell) http://jim.nasby.net
