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From "John H. Embretsen (JIRA)" <derby-...@db.apache.org>
Subject [jira] Updated: (DERBY-981) Errors in Tuning Guide's "Properties case study"
Date Fri, 17 Feb 2006 14:06:25 GMT
     [ http://issues.apache.org/jira/browse/DERBY-981?page=all ]

John H. Embretsen updated DERBY-981:

    Attachment: DERBY-981_v1.diff

Attaching the following files for review/commit:

* "DERBY-981_v1.diff"  -  Patch to fix this issue
* "DERBY-981_v1.stat"  -  svn status file
* "ctunsetprop32443_v1.html"  -  Resulting html file (from Tuning Guide) for review

The following changes are made to src/tuning/ctunsetprop32443.dita by this patch:

* Changed DOCTYPE declaration as suggested by Jeff Levitt (see http://www.nabble.com/-doc-Derby-DITA-documentation-source-DTD-declarations-p2978501.html).
* Updated Copyright statement to include 2006.
* Made the name of the example application consistent throughout the case study, using "MyApp".
* Changed the stated value of derby.storage.pageSize from 8192 to 32768 in the last example.

> Errors in Tuning Guide's "Properties case study"
> ------------------------------------------------
>          Key: DERBY-981
>          URL: http://issues.apache.org/jira/browse/DERBY-981
>      Project: Derby
>         Type: Bug
>   Components: Documentation
>     Versions:,,,,,,,,
>  Environment: All
>     Reporter: John H. Embretsen
>     Assignee: John H. Embretsen
>     Priority: Minor
>      Fix For:
>  Attachments: DERBY-981_v1.diff, DERBY-981_v1.stat, ctunsetprop32443_v1.html
> The tuning guide contains a "Properties case study", demonstrating precedence and persistence
of derby properties; see http://db.apache.org/derby/docs/dev/tuning/ctunsetprop32443.html.
There is at least one factual error and a couple of inaccurate details in this case study:
> 1) The value of the property derby.storage.pageSize that is being used in the last example
should be 32768, not 8192:
> After the example statement 
> CREATE TABLE table4 (a INT, b VARCHAR(10))
> the case study states
> "Derby uses the persistent database-wide property of 8192 for this table, since the database-wide
property set in the previous session is persistent and overrides the system-wide property
set in the derby.properties file."
> In the previous session, however, the database-wide property derby.storage.pageSize is
set to 32768 (not 8192), by doing the following:
> === start quote ===
> You establish a connection to the database and set the value of the page size for all
new tables to 32768 as a database-wide property: 
> CallableStatement cs = 
> cs.setString(1, "derby.storage.pageSize"); 
> cs.setString(2, "32768"); 
> cs.execute(); 
> cs.close(); 
> === end quote ===
> 8192 is the value that is specified in the derby.properties file, which is overridden
by the value (32768) specified in the database.
> (Assuming that the same database is being used).
> 2) Inconsistent use of application name:
> The case study describes persistence/precedence of a derby property by showing different
ways of specifying this property when starting/running an application (embedded Derby). It
seems that the intention was to show this using the same application and database. However,
different application names are used throughout the case study:
> a) java -Dderby.system.home=c:\system_directory MyApp
> b) java -Dderby.system.home=c:\system_directory  -Dderby.storage.pageSize=4096 myApp
> c) java -Dderby.system.home=c:\system_directory myApplication
> Potential confusion may be avoided by using the same application name throughout the
case study.

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