db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Tony Brusseau (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-4422) Extremely slow subqueries when subquerying on strings
Date Fri, 23 Oct 2009 20:55:59 GMT

    [ https://issues.apache.org/jira/browse/DERBY-4422?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12769442#action_12769442
] 

Tony Brusseau commented on DERBY-4422:
--------------------------------------

Not sure why these queries would be flattened. The inner queries are not correlated with the
outter queries. One would think that the inner query would be run first, then the outter query
would be run using the results of the first query.

I tried calling:
CALL SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('BLAH', 'OC_CONCEPTS', NULL);
and get the message:
Error code -1, SQL state 42Y03: 'SYSCS_UTIL.SYSCS_UPDATE_STATISTICS' is not recognized as
a function or procedure.


PS I'm not a DB expert feel free to ignore me if what I say doesn't make sense 8-).



> Extremely slow subqueries when subquerying on strings
> -----------------------------------------------------
>
>                 Key: DERBY-4422
>                 URL: https://issues.apache.org/jira/browse/DERBY-4422
>             Project: Derby
>          Issue Type: Bug
>    Affects Versions: 10.5.3.0
>         Environment: Suse Unix 10.3.
>            Reporter: Tony Brusseau
>         Attachments: tmp2.sql
>
>
> SELECT DISTINCT C.INTERNAL_ID 
> FROM OC_CONCEPTS C
> WHERE
>    (C.INTERNAL_ID IN (SELECT DISTINCT OCS.CONCEPT_ID FROM OC_CONCEPT_STRINGS OCS WHERE
OCS.CONCEPT_ID=1))
> Both queries above are trivial and they are both acting on fully indexed primary key
columns. This query runs just fine. 
> However, when I make the small modification of searching on an indexed text column in
the sub query, it takes over 6 seconds to run, even though both queries independently take
< 1ms run.
> SELECT DISTINCT C.INTERNAL_ID 
> FROM OC_CONCEPTS C
> WHERE
>    (C.INTERNAL_ID IN (SELECT DISTINCT OCS.CONCEPT_ID FROM OC_CONCEPT_STRINGS OCS WHERE
OCS.NL_LC = 'dash'))

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.


Mime
View raw message