Обсуждение: GEQO Benchmark

Hi all,

I'm using the TPC-H Benchmark for testing of performance in PostgreSQL.
But it is composed of only 8 tables, which is not enough to call the GEQO
algorithm.

I don't want to change any of the 22 queries provided by the TPC-H to call
the GEQO, and not lose the credibility of the TPC's tool.

Is there a specific tool for testing queries with large number of tables
(12 or more), or some a documentation of tests carried out in GEQO
Algorithm?

--
Tarcizio Bini

tarcizioab@c3sl.ufpr.br writes:
> I'm using the TPC-H Benchmark for testing of performance in PostgreSQL.
> But it is composed of only 8 tables, which is not enough to call the GEQO
> algorithm.

See
http://www.postgresql.org/docs/8.3/static/runtime-config-query.html#RUNTIME-CONFIG-QUERY-GEQO

particularly geqo_threshold.

            regards, tom lane

Hi,

Of course, the geqo_threshold can be changed so that the geqo be performed in queries that have less than 12 tables. However, we aim to test the GEQO algorithm in conditions where the standard algorithm (dynamic programming) has a high cost to calculate the query plan.

--

Tarcizio Bini

On Wed, 2008-05-28 at 13:13 -0300, Tarcizio Bini wrote:

> Of course, the geqo_threshold can be changed so that the geqo be
> performed in queries that have less than 12 tables. However, we aim to
> test the GEQO algorithm in conditions where the standard algorithm
> (dynamic programming) has a high cost to calculate the query plan.

My understanding is the GEQO cannot arrive at a better plan than the
standard optimizer, so unless you wish to measure planning time there
isn't much to test. What is the quality of the plans it generates? Well
that varies according to the input; sometimes it gets the right plan,
other times it doesn't get close.

--
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support

I'm interested in the response time instead of the quality of it, that is, if this response is (or not) a best plan. Thus, my interest on the response time is to compare the GEQO algorithm with other solutions for optimization of queries, more specificaly when there are 12 or more tables evolved. Accordingly, the algorithm of dynamic programming becomes hard because of the computational cost to obtain the optimal plan.

My question is to know what tool or method was used to test the GEQO algorithm or if there is some documentation that explain how the geqo was tested.

Regards,

Tarcizio Bini