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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3847) Tuning Guide lacks information on turning off Derby property settings
Date Mon, 06 Oct 2008 21:53:44 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12637265#action_12637265
] 

Dag H. Wanvik commented on DERBY-3847:
--------------------------------------

Thanks for the new patch, Kim! Looks good!

Re "true"/"false"; checking Boolean.valueOf(String) - which Derby uses - it says:

  public static Boolean valueOf(String s)
  Returns a Boolean with a value represented by the specified string. 
  The Boolean returned represents a true value if the string argument is not null and is equal,
  ignoring case, to the string "true".

So I guess you can keep the current wording :)

Reading "Persistence of properties" again, I get fuzzy (feel free to ignore :-)

> :
> Typically, it is in effect until you
> explicitly change the property or until you set a system-wide property
> with precedence over database-wide properties (see Precedence of
> properties).

The last sentence is perhaps a bit troublesome; it can lead a user into
believing a system-wide property always takes presedence over a
database-wide property, whereas this depends on how it has been set.
Not sure how to phrase it better, though :)

> If you set it in the derby.properties file, a property persists
> until:
> - That value is changed 

(if dynamic; if static until system is rebooted)

> - The file is removed from the system

(if dynamic; if static until system is rebooted)

Not sure you can actually remove derby.properties when the VM is running, though;
it may be OS dependent..


> Tuning Guide lacks information on turning off Derby property settings
> ---------------------------------------------------------------------
>
>                 Key: DERBY-3847
>                 URL: https://issues.apache.org/jira/browse/DERBY-3847
>             Project: Derby
>          Issue Type: Bug
>          Components: Documentation
>    Affects Versions: 10.4.1.3
>            Reporter: Kim Haase
>            Assignee: Kim Haase
>            Priority: Minor
>         Attachments: ctunproper22250.html, ctunproper22250.html, DERBY-3847-2.diff, DERBY-3847-2.zip,
DERBY-3847-3.diff, DERBY-3847-4.diff, DERBY-3847.diff, DERBY-3847.stat, DERBY-3847.zip
>
>
> The documentation of how to turn off Derby properties is spotty. Dag Wanvik reports that
"I checked the code, and when you set a database property to a null value, that property is
removed from the list of database properties; i.e. the situation is back to where you were
before it was first set, so the built-in defaults apply again (or system properties if there
are any)."
> The behavior for turning off user settings is slightly different and is documented in
several places; it's the general case that seems to be missing. This information needs to
be added to the description of Derby properties in the Tuning Guide, probably in the general
topic "Derby properties" (http://db.apache.org/derby/docs/dev/tuning/ctunproper22250.html).

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