Re: Please Help: PostgreSQL performance Optimization
От | Jamal Ghaffour |
---|---|
Тема | Re: Please Help: PostgreSQL performance Optimization |
Дата | |
Msg-id | 43C66D67.1000502@elios-informatique.fr обсуждение исходный текст |
Ответ на | Please Help: PostgreSQL performance Optimization (Jamal Ghaffour <Jamal.Ghaffour@elios-informatique.fr>) |
Ответы |
Re: Please Help: PostgreSQL performance Optimization
Re: Please Help: PostgreSQL performance Optimization |
Список | pgsql-performance |
Jamal Ghaffour a écrit : <blockquote cite="mid43C66742.9060104@elios-informatique.fr" type="cite"></blockquote><font><fontcolor="#000000"> <pre style="margin: 0em;">Hi, <font face="Arial, Helvetica, sans-serif"> I'm working on a project, whose implementation deals with PostgreSQL. A brief description of our application is given below.</font> I'm running version 8.0 on a dedicated server 1Gb of RAM. my database isn't complex, it contains just 2 simple tables. <tt> CREATE TABLE cookies ( domain varchar(50) NOT NULL, path varchar(50) NOT NULL, name varchar(50) NOT NULL, principalidvarchar(50) NOT NULL, host text NOT NULL, value text NOT NULL, secure bool NOT NULL, timestamp timestampwith time zone NOT NULL DEFAULT CURRENT_TIMESTAMP+TIME '04:00:00', PRIMARY KEY (domain,path,name,principalid) ) CREATE TABLE liberty ( principalid varchar(50) NOT NULL, requestid varchar(50) NOT NULL, spassertionurl text NOT NULL, libertyversion varchar(50) NOT NULL, relaystate varchar(50) NOT NULL, PRIMARY KEY (principalid) ) </tt>I'm developping an application that uses the libpqxx to execute psql queries on the database and have to execute 500 requests at the same time. <tt> UPDATE cookies SET host='ping.icap-elios.com', value= '54E5B5491F27C0177083795F2E09162D', secure=FALSE, timestamp=CURRENT_TIMESTAMP+INTERVAL '14400 SECOND' WHERE domain='ping.icap-elios.com' AND path='/tfs' AND principalid='192.168.8.219' AND name='jsessionid'</tt> <tt>SELECT path, upper(name) AS name, value FROM cookies WHERE timestamp<CURRENT_TIMESTAMP AND principalid='192.168.8.219'AND secure=FALSE AND (domain='ping.icap-elios.com' OR domain='.icap-elios.com')</tt> I have to notify that the performance of is extremely variable and irregular. I can also see that the server process uses almost 100% of a CPU. I'm using the default configuration file, and i m asking if i have to change some paramters to have a good performance. Any help would be greatly appreciated. Thanks,</pre> </font></font> Hi,<br /><br /> There are some results that can give you <span class="def-example">concrete </span>idea about my problem: <br /> when i 'm launching my test that executes in loop mannerthe SELECT and UPDATE queries described above, i'm obtaining this results:<br /><br /> UPDATE Time execution :0s:5225 us<br /> SELECT Time execution :0s: 6908 us<br /><br /> 5 minutes Later: <br /><br /> UPDATE Time execution :0s:6125 us<br /> SELECT Time execution :0s: 10928 us<br /><br /> 5 minutes Later: <br /><br /> UPDATE Time execution :0s:5825 us<br /> SELECT Time execution :0s: 14978 us<br /><br /> As you can see , the time execution of the SELECT requestis growing relatively to time and not the UPDATE time execution. <br /> I note that to stop the explosion of theSelect time execution, i m using frequently the vaccum query on the cookies table.<br /> Set the autovacuum parmaeterin the configuation file to on wasn't able to remplace the use of the vaccum command, and i don't know if this behaivouris normal?<br /><br /> Thanks,<br /> Jamal<br />
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