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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 Thu, 02 Oct 2008 22:11:44 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3847?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12636485#action_12636485

Dag H. Wanvik commented on DERBY-3847:

Hi Kim, thanks for the new patch version. I have a couple of small comments:


* As it now stands, it looks kind of weird that the section starts by
explaining how you can *turn off* properties. I think we should first
explain, or point to where it is explained, how to turn them on first?

> (A system property set programmatically takes precedence over a
> system property set in the derby.properties file.) 

I think it would be clearer (at the expense of verbosity)
to explicitly list the search order again
before trying to explain how this would work, e.g. some such:

To disable or turn off a database-wide property setting, set its value
to null. What value applies after this is done?  To answer that,
recall that the search order is (ref to where explained first time?):

1. [*] System-wide properties set programmatically (as a command-line
   option to the JVM when starting the application or within application
2. Database-wide properties 
3. [*] System-wide properties set in the derby.properties file

[*] Not consulted if derby.database.propertiesOnly is set to true.

Assuming we are *not* using programmatically set system properties,
setting the database-wide property to null has the effect of removing
the property from the list of database properties and restoring the
system property setting from derby.properties if there is one.  As always, if no
value can be determined from the search, the builtin default applies.

* "be sure to trim extra spaces around the word true"

true or false, as the case may be

* Some static properties can not be disabled once enabled, even with a reboot,
  notably derby.database.sqlAuthorization. I think this applies for some others as well,
  have you seen any list of those? Do the conglomerate properties fall into this category..?

> 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:
>            Reporter: Kim Haase
>            Assignee: Kim Haase
>            Priority: Minor
>         Attachments: ctunproper22250.html, ctunproper22250.html, DERBY-3847-2.diff, DERBY-3847-3.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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