Derby Config Question

[Philippe Lamote <ph...@mac.com>]

Hi List,

I'm new to Derby so if this is too trivial, don't mind rubbing my  
nose into it ;-)

I have in my setup one place where I keep all the configuration  
together. (jdoconfig.properties, Spring Configuration, ... )
Of course this would be the obvious place to also put the  
"derby.properties". Yet this is not the place where I put the Derby  
data files themselves.

So, in short, this would be the "package" layout:
- src/.../conf/derby.properties  (will be copied to bin/.../conf @  
compile time)
- data/... (the Derby data dir)

But then I read in the derby Manual: "You can set persistent system- 
wide properties in a text file called derby.properties, which
must be placed in the directory specified by the derby.system.home  
property."

I understand that "derby.system.home" would be this data directory  
and this is not where I want to put the Derby properties.
I thought of this to solve it: in the general Application init  
method, adding this:

Properties derbyProperties = new Properties();

		try{
		System.out.println("User dir property is "+ System.getProperty 
("user.dir"));
		String pathname = System.getProperty("user.dir") + "/src/.../conf/ 
derby.properties";
		
		derbyProperties.load(new FileInputStream(new File(pathname)));
		}

		catch (IOException ioe) {
			System.out.println("Couldn't load Derby properties." + ioe);
		}
		Properties systemprops = System.getProperties();
		systemprops.putAll(derbyProperties);		// adds the Derby Properties  
to this JVM's System Properties.


--> Is this OK for Derby? And will the properties specified there  
indeed be set & active upon the next connect?  (and not make it put  
all the dat files in my conf folder)

Thx,
Phil

Re: Derby Config Question

[John Embretsen <Jo...@Sun.COM>]

Philippe Lamote wrote:

> Hi List, 
> 
> I'm new to Derby so if this is too trivial, don't mind rubbing my nose 
> into it ;-)
> 
> I have in my setup one place where I keep all the configuration 
> together. (jdoconfig.properties, Spring Configuration, ... )
> Of course this would be the obvious place to also put the 
> "derby.properties". Yet this is not the place where I put the Derby data 
> files themselves. 
> 
> So, in short, this would be the "package" layout:
> - src/.../conf/derby.properties  (will be copied to bin/.../conf @ 
> compile time)
> - data/... (the Derby data dir)
> 
> But then I read in the derby Manual: "You can set persistent system-wide 
> properties in a text file called /derby.properties/, which 
> must be placed in the directory specified by the /derby.system.home/ 
> property."
> 
> I understand that "derby.system.home" would be this data directory and 
> this is not where I want to put the Derby properties.
> I thought of this to solve it: in the general Application init method, 
> adding this:

<snip example of setting system properties programmatically>

> --> Is this OK for Derby? And will the properties specified there indeed 
> be set & active upon the next connect?  (and not make it put all the dat 
> files in my conf folder)


Yes, I think this will work, as long as you connect to the database (or start 
an embedded Derby server) from the same instance of the JVM.

I would, however, like to point out that properties specified 
programmatically (which is your solution) have higher precedence than 
properties that are automatically picked up by Derby from the 
derby.properties file; see the Derby Tuning Guide, 
http://db.apache.org/derby/docs/dev/tuning/. This may be a corner case, but:

Quoting http://db.apache.org/derby/docs/dev/tuning/ctunsetprop23308.html:

<quote>

This means, for example, that system-wide properties set programmatically 
override database-wide properties and system-wide properties set in the 
derby.properties file, and that database-wide properties override system-wide 
properties set in the derby.properties file.

</quote>

So, if (for example) you previously relied on database-wide properties 
overriding system-wide properties in the derby-properties file as it was 
automatically picked up by Derby, you will find that this no longer happens, 
since the properties are set programmatically instead, thus overriding the 
database-wide properties.

Another possible work-around is to specify "full" database paths (absolute or 
relative to derby.system.home), see 
http://wiki.apache.org/db-derby/DatabaseNamesRelativeAbsolute.


-- 
John

Re: Derby Config Question

[Rajesh Kartha <ka...@gmail.com>]

Hi Philippe,

I think this should work.
In your case the application is loading and setting all the Derby system 
properties, whereas
following the Derby documentation way - pointing the derby.system.home 
to the derby.properties, Derby would
have done it for you.

http://db.apache.org/derby/manuals/tuning/perf14.html#HDRSII-SETPROP-13074

-Rajesh




Philippe Lamote wrote:

> Hi List, 
>
> I'm new to Derby so if this is too trivial, don't mind rubbing my nose 
> into it ;-)
>
> I have in my setup one place where I keep all the configuration 
> together. (jdoconfig.properties, Spring Configuration, ... )
> Of course this would be the obvious place to also put the 
> "derby.properties". Yet this is not the place where I put the Derby 
> data files themselves. 
>
> So, in short, this would be the "package" layout:
> - src/.../conf/derby.properties  (will be copied to bin/.../conf @ 
> compile time)
> - data/... (the Derby data dir)
>
> But then I read in the derby Manual: "You can set persistent 
> system-wide properties in a text file called /derby.properties/, which 
> must be placed in the directory specified by the /derby.system.home/ 
> property."
>
> I understand that "derby.system.home" would be this data directory and 
> this is not where I want to put the Derby properties.
> I thought of this to solve it: in the general Application init method, 
> adding this:
>
> Properties derbyProperties = new Properties();
>
> try{
> System.out.println("User dir property is "+ 
> System.getProperty("user.dir")); 
> String pathname = System.getProperty("user.dir") + 
> "/src/.../conf/derby.properties"; 
> derbyProperties.load(new FileInputStream(new File(pathname)));
> }
>
> catch (IOException ioe) {
> System.out.println("Couldn't load Derby properties." + ioe);
> }
> Properties systemprops = System.getProperties();
> systemprops.putAll(derbyProperties); // adds the Derby Properties to 
> this JVM's System Properties.
>
>
> --> Is this OK for Derby? And will the properties specified there 
> indeed be set & active upon the next connect?  (and not make it put 
> all the dat files in my conf folder)
>
> Thx, 
> Phil
>
>
>
>