Le 20/03/2014 18:13, Torsten Förtsch a écrit :
On 20/03/14 17:57, Jean-Max Reymond wrote:
I have a very complex view zinfoexp and running the view as:
SELECT * FROM zinfoexp WHERE idmembre in (1,84)
take 2700 ms
So, I try another syntax:
SELECT * FROM zinfoexp WHERE idmembre = 1
union
SELECT * FROM zinfoexp WHERE idmembre = 84
and for me, two calls to my view takes a lot of time (may be x2) and it
takes 134 ms !
try
SELECT * FROM zinfoexp WHERE idmembre=1 OR idmembre=84
This will probably be even faster.
Also, the 2 statements of your's are not semantically equal. UNION
implies DISTINCT, see:
select * from (values (1), (1), (2)) t(i) UNION select 19;
i
----
19
1
2
(3 rows)
What you want is UNION ALL:
select * from (values (1), (1), (2)) t(i) UNION ALL select 19;
i
----
1
1
2
19
(4 rows)
Torsten
same numbers with DISTINCT and UNION ALL (construction of VIEW does an
implicit DISTINCT).
--
Jean-Max Reymond
Éruption de l'Etna: http://jmreymond.free.fr/Etna2002
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