Re: [PATCHES] Bitmapscan changes

Joshua D. Drake wrote:
> Heikki Linnakangas wrote:
>> Joshua D. Drake wrote:
>>> This URL is not working:
>>>
>>>
>>> http://community.enterprisedb.com/git/git-perfunittests-20070222.tar.gz
>> Sorry about that, typo in the filename. Fixed.
>>
>>
> Here are my results on a modest 3800X2 2 Gig of ram, RAID 1 dual SATA

Thanks for looking into this, though that test alone doesn't really tell
us anything. You'd have to run the same tests with and without clustered
indexes enabled, and compare. With the default settings the test data
fits in memory anyway, so you're not seeing the I/O benefit but only the
CPU overhead.

Attached is a larger test case with a data set of > 2 GB. Run the
git_demo_init.sql first to create tables and indexes, and
git_demo_run.sql to perform selects on them. The test runs for quite a
long time, depending on your hardware, and print the time spent on the
selects, with and without clustered index.

You'll obviously need to run it with the patch applied. I'd suggest to
enable stats_block_level to see the effect on buffer cache hit/miss ratio.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com