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From "Andy Jefferson (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-1996) DatabaseMetaData.getColumns() takes long time to return columns for a particular schema of Apache JDO TCK
Date Tue, 05 Aug 2008 14:20:44 GMT

    [ https://issues.apache.org/jira/browse/DERBY-1996?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12619891#action_12619891
] 

Andy Jefferson commented on DERBY-1996:
---------------------------------------

Any comment on when (approx) DatabaseMetaData.getColumns will be capable of giving reasonable
performance in situations like this? or is there some SELECT that we can do ourselves to get
the same basic information without having to go through getColumns() ?? Thx

> DatabaseMetaData.getColumns() takes long time to return columns for a particular schema
of Apache JDO TCK
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-1996
>                 URL: https://issues.apache.org/jira/browse/DERBY-1996
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.2.1.6
>            Reporter: Andy Jefferson
>         Attachments: testcase.zip
>
>
> When running the Apache JDO "TCK", JPOX needs to query the columns for a particular schema,
and so uses DatabaseMetaData.getColumns(null, schemaName, null, null). This takes the order
of 3 minutes on a dual-core Pentium 3GHz (with large ram). I've cut the JPOX part down to
a stand-alone test (will attach it).
> Thing to note is that with only the schema files d_* installed it takes the order of
20secs. When the schema_* files are also installed then performance goes downhill fast (even
though they are in different schemas ... all *.sql file represents a different schema). No
point in me postulating what could be the issue since you guys are the Derby experts.

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