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From Apache Wiki <wikidi...@apache.org>
Subject [Db-derby Wiki] Update of "UndocumentedDerbyBehavior" by KimHaase
Date Tue, 08 Oct 2013 19:00:58 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Db-derby Wiki" for change notification.

The "UndocumentedDerbyBehavior" page has been changed by KimHaase:
https://wiki.apache.org/db-derby/UndocumentedDerbyBehavior?action=diff&rev1=6&rev2=7

  <<TableOfContents>>
+ 
  = Introduction =
- This page lists the undocumented Derby behavior which can be handy to the users at the same
time, the users should be aware that this behavior is not documented and hence it is subject
to change at anytime.
+ This page lists undocumented Derby behavior which can be handy for users. At the same time,
users should be aware that this behavior is not documented, and hence it is subject to change
at anytime.
  
  = Client side tracing under Network Server =
- Currently, the client tracing can be enabled by setting jdbc url attributes or through setXXX
methods on the DataSource or by calling DriverManager.setLogWriter method (More information
on these options can be found in the Server and Administration Guide). All these options require
changing the client code which may not be a feasible option for a deployed client application.
To get around this, in Derby 10.3, 2 new JVM properties([[http://issues.apache.org/jira/browse/DERBY-1275|DERBY-1275]])
have been added. They are namely, derby.client.traceLevel and derby.client.traceDirectory.
When the client application is started, the users can include these 2 JVM properties to start
the client side tracing. eg
+ Currently, the client tracing can be enabled by setting jdbc url attributes or through setXXX
methods on the DataSource or by calling DriverManager.setLogWriter method (More information
on these options can be found in the Server and Administration Guide). All these options require
changing the client code which may not be a feasible option for a deployed client application.
To get around this, in Derby 10.3, 2 new JVM properties([[http://issues.apache.org/jira/browse/DERBY-1275|DERBY-1275]])
have been added. They are namely, derby.client.traceLevel and derby.client.traceDirectory.
When the client application is started, the users can include these 2 JVM properties to start
the client side tracing. eg java -Dderby.client.traceDirectory=./traceDir -Dderby.client.traceLevel=64
clientApplication
- java -Dderby.client.traceDirectory=./traceDir -Dderby.client.traceLevel=64 clientApplication
  
- When running under security manager, read permission for these properties is required. 
If permission to read the properties is not allowed, the properties will be ignored and tracing
will not be affected.  
+ When running under security manager, read permission for these properties is required. 
If permission to read the properties is not allowed, the properties will be ignored and tracing
will not be affected.
  
+ = Undocumented optimizer overrides =
+ "Overriding the default optimizer behavior" in "Tuning Derby" (http://db.apache.org/derby/docs/10.10/tuning/ctunoptimzoverride.html)
documents four optimizer overrides (constraint, index, joinOrder, joinStrategy). Derby supports
some additional ones that are not documented. They are as follows:
+ 
+  * bulkFetch (must be an integer greater than 0 and not updatable)
+  * hashInitialCapacity (must be an integer greater than 0)
+  * hashLoadFactor (must be a float value greater than 0.0 and less than or equal to 1.0)
+  * hashMaxCapacity (must be an integer greater than 0)
+  * useStatistics (must be "true" or "false")
+ 

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