On 08/02/12 21:15, Peter van Hardenberg wrote:
Having read the thread, I don't really see how I could study what a
more principled value would be.
That said, I have access to a very large fleet in which to can collect
data so I'm all ears for suggestions about how to measure and would
gladly share the results with the list.
Peter
On Wed, Feb 8, 2012 at 5:39 PM, Scott Marlowe<scott.marlowe@xxxxxxxxx> wrote:
On Wed, Feb 8, 2012 at 5:50 PM, Josh Berkus<josh@xxxxxxxxxxxx> wrote:
On 2/7/12 4:59 PM, Peter van Hardenberg wrote:
Per the thread from last month, I've updated the default
random_page_cost on Heroku Postgres to reduce the expected cost of a
random_page on all new databases.
This is because Heroku uses AWS storage, which has fast seeks but poor
throughput compared to internal disk on a standard system, BTW.
Also judging by the other thread, it might be something to stop closer
to 1.2 to 1.4 or something.
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You can execute several queries with the three different values provided
by Scott and Josh.
- SET random_page_cost = 2.0
First execution of the queries with EXPLAIN ANALYZE
- SET random_page_cost = 1.4
Second execution of the queries with EXPLAIN ANALYZE
- SET random_page_cost = 1.2
Second execution of the queries with EXPLAIN ANALYZE
And then, you can compare the pattern behind these queries executions
Regards,
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