Re: Performance comparison between Postgres and Greenplum

From: Alex Goncharov <alex-goncharov(at)comcast(dot)net>
To: Suvankar Roy <suvankar(dot)roy(at)tcs(dot)com>
Cc: alex-goncharov(at)comcast(dot)net, pgsql-performance(at)postgresql(dot)org
Subject: Re: Performance comparison between Postgres and Greenplum
Date: 2009-07-15 13:18:12
Message-ID: E1MR4NA-0007Gd-FJ@daland.home
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,--- You/Suvankar (Wed, 15 Jul 2009 18:32:12 +0530) ----*
| Yes, I have got 2 segments and a master host. So, in a way processing
| should be faster in Greenplum.

No, it should not: it all depends on your data, SQL statements and
setup.

In my own experiments, with small amounts of stored data, PostgreSQL
beats Greenplum, which doesn't surprise me a bit.

You need to know where most of the execution time goes -- maybe to
sorting? And sorting in Greenplum, isn't it done on one machine, the
master host? Why would that be faster than in PostgreSQL?
|
| For other queries though, results are satisfactory or at least comparable,
| like-
|
| select distinct so_no, serial_no from observation_all;
| in postgres it takes - 1404.238 ms
| in gp it takes - 1217.283 ms

No surprise here: the data is picked by multiple segment hosts and
never sorted on the master.

-- Alex -- alex-goncharov(at)comcast(dot)net --

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