From: tank.zhang <6220104@qq.com>
To: pgsql-performance@postgresql.org
Subject: Re: Postgresql Sort cost Poor performance?
Date: Tue, 2 Apr 2019 00:00:09 -0700 (MST)
Message-ID: <1554188409091-0.post@n3.nabble.com> (raw)
In-Reply-To: <CADGuD5DDHfwsU+6MjwfmvUSYHc3K7bDe9Tf7jS41ybTOpQgxag@mail.gmail.com>
References: <1554111914781-0.post@n3.nabble.com>
<CADGuD5DDHfwsU+6MjwfmvUSYHc3K7bDe9Tf7jS41ybTOpQgxag@mail.gmail.com>
1、DISTINCT response time is fast without being added
qis3_dp2=# SELECT COUNT(*) AS CHECKCARNUM FROM QIS_CARPASSEDSTATION A WHERE
1=1 AND A.SSTATIONCD = 'VQ3_LYG' AND A.SLINENO IN ( '1F' , '2F' , '3F' ) AND
A.DWORKDATE >= TO_DATE('2017-02-11','YYYY-MM-DD') AND A.DWORKDATE <=
TO_DATE('2019-03-11','YYYY-MM-DD');
checkcarnum
-------------
2142215
(1 row)
*Time: 2237.970 ms (00:02.238)*
qis3_dp2=#
2、 Adding a DISTINCT response time was very slow
qis3_dp2=# SELECT COUNT(DISTINCT SVIN) AS CHECKCARNUM FROM
QIS_CARPASSEDSTATION A WHERE 1=1 AND A.SSTATIONCD = 'VQ3_LYG' AND A.SLINENO
IN ( '1F' , '2F' , '3F' ) AND A.DWORKDATE >=
TO_DATE('2017-02-11','YYYY-MM-DD') AND A.DWORKDATE <=
TO_DATE('2019-03-11','YYYY-MM-DD');
checkcarnum
-------------
1071367
(1 row)
*Time: 38979.246 ms (00:38.979)*
--
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To: pgsql-performance@postgresql.org
Cc: 6220104@qq.com
Subject: Re: Postgresql Sort cost Poor performance?
In-Reply-To: <1554188409091-0.post@n3.nabble.com>
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