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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-2986) Query involving CASE statement significantly slower in 10.3.1.4 than in 10.2.2.0
Date Mon, 29 Jun 2009 14:05:47 GMT

     [ https://issues.apache.org/jira/browse/DERBY-2986?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Dag H. Wanvik updated DERBY-2986:
---------------------------------

    Derby Categories: [Performance]

> Query involving CASE statement significantly slower in 10.3.1.4 than in 10.2.2.0
> --------------------------------------------------------------------------------
>
>                 Key: DERBY-2986
>                 URL: https://issues.apache.org/jira/browse/DERBY-2986
>             Project: Derby
>          Issue Type: Bug
>    Affects Versions: 10.3.1.4
>         Environment: Windows XP
>            Reporter: James F. Adams
>            Assignee: A B
>             Fix For: 10.3.2.1, 10.4.1.3
>
>         Attachments: d2986_notTested_v1.patch, d2986_test.patch
>
>
> A select of a CASE statement that performed acceptably in 10.2.2.0 is very slow in 10.3.1.4
the first time it is executed.
> The following example ij script:
> ELAPSEDTIME ON;
> CREATE table test1(id integer);
> CREATE table test2(id varchar(10));
> SELECT CASE  WHEN t.id = 1 THEN 'a'
>              WHEN t.id = 2 THEN 'b'
>              WHEN t.id = 3 THEN 'c'
>              WHEN t.id = 4 THEN 'd'
>              WHEN t.id = 5 THEN 'e'
>              WHEN t.id = 6 THEN 'f'
>              WHEN t.id = 7 THEN 'g'
>              WHEN t.id = 8 THEN 'h'
>              WHEN t.id = 11 THEN 'i'
>              WHEN t.id = 12 THEN 'j' 
>              WHEN t.id = 15 THEN 'k'
>              WHEN t.id = 16 THEN 'l'
>              WHEN t.id = 23 THEN 'm' 
>              WHEN t.id = 24 THEN 'n'
>              WHEN t.id = 27 THEN 'o'
>              WHEN t.id = 31 THEN 'p'
>              WHEN t.id = 41 THEN 'q'
>              WHEN t.id = 42 THEN 'r'
>              WHEN t.id = 50 THEN 's'
>              ELSE (SELECT t2.id
>                      FROM test2 t2
>                   )
>        END
> FROM test1 t;
> When run on 10.2.2.0 the select results in ELAPSED TIME = 187 milliseconds.
> When run on 10.3.1.4 the select results in ELAPSED TIME = 62281 milliseconds.

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