Script to compute randon page cost
Linux RedHat 7.3 (ext3, kernel 2.4.18-3)
512MB Ram
AMD Athlon 500
IBM 120GB IDE
[hs@backup hs]$ ./randcost.sh /data/db/
Collecting sizing information ...
Running random access timing test ...
Running sequential access timing test ...
random_page_cost = 0.901961
[hs@backup hs]$ ./randcost.sh /data/db/
Collecting sizing information ...
Running random access timing test ...
Running sequential access timing test ...
random_page_cost = 0.901961
Great script - it should be in contrib.
Hans
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*Cybertec Geschwinde u Schoenig*
Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria
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www.postgresql.at <http://www.postgresql.at>, cluster.postgresql.at
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Assuming it's giving out correct information, there seems to be a lot of
evidence for dropping the default random_page_cost to 1...
Chris
Show quoted text
-----Original Message-----
From: pgsql-hackers-owner@postgresql.org
[mailto:pgsql-hackers-owner@postgresql.org]On Behalf Of Hans-J�rgen
Sch�nig
Sent: Monday, 9 September 2002 4:06 PM
To: pgsql-hackers
Subject: [HACKERS] Script to compute randon page costLinux RedHat 7.3 (ext3, kernel 2.4.18-3)
512MB Ram
AMD Athlon 500
IBM 120GB IDE[hs@backup hs]$ ./randcost.sh /data/db/
Collecting sizing information ...
Running random access timing test ...
Running sequential access timing test ...random_page_cost = 0.901961
[hs@backup hs]$ ./randcost.sh /data/db/
Collecting sizing information ...
Running random access timing test ...
Running sequential access timing test ...random_page_cost = 0.901961
Great script - it should be in contrib.
Hans
--
*Cybertec Geschwinde u Schoenig*
Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria
Tel: +43/1/913 68 09; +43/664/233 90 75
www.postgresql.at <http://www.postgresql.at>, cluster.postgresql.at
<http://cluster.postgresql.at>, www.cybertec.at
<http://www.cybertec.at>, kernel.cybertec.at <http://kernel.cybertec.at>---------------------------(end of broadcast)---------------------------
TIP 4: Don't 'kill -9' the postmaster
Christopher Kings-Lynne wrote:
Assuming it's giving out correct information, there seems to be a lot of
evidence for dropping the default random_page_cost to 1...Chris
Some time ago Joe Conway suggest a tool based on a genetic algorithm
which tries to find the best parameter settings.
As input the user could use a set of SQL statements. The algorithm will
try to find those settings which lead to the lowest execution time based
on the set of SQL.
What about something like that?
This way people could tune the database theirselves.
Hans
--
*Cybertec Geschwinde u Schoenig*
Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria
Tel: +43/1/913 68 09; +43/664/233 90 75
www.postgresql.at <http://www.postgresql.at>, cluster.postgresql.at
<http://cluster.postgresql.at>, www.cybertec.at
<http://www.cybertec.at>, kernel.cybertec.at <http://kernel.cybertec.at>
"Christopher Kings-Lynne" <chriskl@familyhealth.com.au> writes:
Assuming it's giving out correct information, there seems to be a lot of
evidence for dropping the default random_page_cost to 1...
The fact that a lot of people are reporting numbers below 1 is
sufficient evidence that the script is broken. A value below 1
is physically impossible.
regards, tom lane
On Mon, 2002-09-09 at 01:16, Hans-Jürgen Schönig wrote:
Christopher Kings-Lynne wrote:
Assuming it's giving out correct information, there seems to be a lot of
evidence for dropping the default random_page_cost to 1...Chris
Some time ago Joe Conway suggest a tool based on a genetic algorithm
which tries to find the best parameter settings.
As input the user could use a set of SQL statements. The algorithm will
try to find those settings which lead to the lowest execution time based
on the set of SQL.What about something like that?
This way people could tune the database theirselves.
I actually had starting coding a tool like this, but have become
distracted with other things. I plan on continuing with it maybe next
week. If anyone has suggestions, please let me know...
--brett
--
Brett Schwarz
brett_schwarz AT yahoo.com