On Fri, Feb 20, 2009 at 2:48 PM, Jonah H. Harris
<jonah.harris@gmail.com> wrote:
Having this said, the benchmark is not as unfair as you thought. I've
taken care to prepare all databases to meet similar values for their
cache, buffers and I/O configuration (to what's possible given their
differences), and the I've left the rest as comes by default (for
Oracle I've used the OLTP template).
Oracle's buffer cache is different than Postgres'. And there are several other tuning paramaters which control how the buffer cache and I/O between cache and disk is performed. Making them the same size means nothing. And, as I said, you still didn't mention other important tuning parameters in MySQL, Postgres, or Oracle. So either you don't know about them, or you didn't bother to tune them, which is odd if you were trying to run a truly comparative benchmark.
Also forgot to ask, what block size did you use in Oracle? You mentioned tuning the shared pool, but you didn't specify db_cache_size or whether you were using automatic SGA tuning. Were those not tuned?
--
Jonah H. Harris, Senior DBA
myYearbook.com