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From "Bryan Pendleton (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3892) Query execution hangs
Date Wed, 01 Oct 2008 23:34:44 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3892?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12636241#action_12636241
] 

Bryan Pendleton commented on DERBY-3892:
----------------------------------------

Here are some starting points for researching performance problems:
http://wiki.apache.org/db-derby/PerformanceDiagnosisTips

Knowing the query plan would be very interesting. To get that, you
may wish to start by trimming your data set down to a smaller number
of records, so that the query runs in a more timely fashion.

You might also wish to post a message to derby-users, rather than
filing a bug, as that might get you more suggestions for how to
improve performance.

> Query execution hangs
> ---------------------
>
>                 Key: DERBY-3892
>                 URL: https://issues.apache.org/jira/browse/DERBY-3892
>             Project: Derby
>          Issue Type: Bug
>    Affects Versions: 10.4.1.3, 10.4.2.0
>         Environment: OS: Windows Vista
> Application environment: Java 1.5 Swing Application using Derby DB in the embedded mode
as part of the application.
>            Reporter: Georgi Hristov
>
> Having the following db schema:
> CREATE TABLE Messaged_Users (ACCOUNT_ID VARCHAR(20) NOT NULL, 
>       USER_ID VARCHAR(20) NOT NULL,
>       DATE TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
>       STATUS INT DEFAULT 0,
>       CONSTRAINT PK_ACC_USER_ID PRIMARY KEY (ACCOUNT_ID, USER_ID))
> CREATE TABLE Users (USER_ID VARCHAR(20) NOT NULL CONSTRAINT USER_ID_PK PRIMARY KEY, 
>       USER_NAME VARCHAR(50) NOT NULL)
> with approximately 100,000 records in each table and trying to execute the following
query:
>       PreparedStatement searchStatement = conn.prepareStatement("SELECT b.USER_ID, b.USER_NAME
FROM Users a JOIN Messaged_Users b ON    a.USER_ID=b.USER_ID AND a.ACCOUNT_ID=(?)");
>       searchStatement.setString(1, "5533232");
>       ResultSet foundUsers = searchStatement.executeQuery();
> the executeQuery method actually never ends. I've waited for more than 30 mins and it
didn't finish. I've tried it really many times but without any progress the query just hangs.
I presume that this is definitely a bug in the derby db which should be fixed. Please note
also that this fix is very urgent for us so that we can deliver our application. 
> Thanks in advance for looking into this issue.
>  
>  

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