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https://issues.apache.org/jira/browse/DERBY-6220?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rick Hillegas updated DERBY-6220:
---------------------------------
Attachment: derby-6220-01-aa-newSystemFunction.diff
Attaching derby-6220-01-aa-newSystemFunction.diff. This patch would add a new
system function for reporting what Derby thinks a property resolves to.
This patch simply hard-codes the analysis provided on this JIRA. The patch adds
a method to PropertyUtil which applies the rules on this JIRA to all of the
documented Derby properties except for NO_AUTO_BOOT. I omitted that property
because I was a bit baffled about how to look up the property set in
service.properties when outside the store after boot time.
The new PropertyUtil method is then wrapped by a new system function:
VARCHAR( 32672 ) SYSCS_UTIL.SYSCS_GET_PROPERTY( IN PROPERTY_NAME
VARCHAR(32672) )
The new system function behaves as follows:
o Applies the rules described on this JIRA to resolve a documented property
name (other than NO_AUTO_BOOT). The result could be null. No attempt is made to
further resolve a property which is null after applying these rules. That is,
no attempt is made to look up default values hard-coded in the custom logic
inside Derby modules.
o Raises an exception if passed an undocumented property (or NO_AUTO_BOOT).
The following script gives an example of running this new system function:
connect 'jdbc:derby:memory:db;create=true';
create function setSystemProperty( propertyName varchar( 32672 ), propertyValue
varchar( 32672 ) )
returns varchar( 32672 )
language java parameter style java no sql
external name 'java.lang.System.setProperty';
-- no value yet (call the new system function)
values syscs_util.syscs_get_property( 'derby.authentication.builtin.saltLength'
);
-- set the property at the system level
values setSystemProperty( 'derby.authentication.builtin.saltLength', '50' );
-- now it has a value (call the new system function)
values syscs_util.syscs_get_property( 'derby.authentication.builtin.saltLength'
);
-- set a different value in the database too
call syscs_util.syscs_set_database_property(
'derby.authentication.builtin.saltLength', '90' );
-- but we still get the system value because of Derby's rules (call the new
system function)
values syscs_util.syscs_get_property( 'derby.authentication.builtin.saltLength'
);
-- unless we specify database properties only
call syscs_util.syscs_set_database_property( 'derby.database.propertiesOnly',
'true' );
-- and now we get the value stored in the database (call the new system
function)
values syscs_util.syscs_get_property( 'derby.authentication.builtin.saltLength'
);
A battery of tests would be needed if we decided to add this proposed new
system function.
This approach could be the basis for a more complete solution. However, there
is no denying that this approach is brittle as-is. I would appreciate feedback
about whether people think this approach is work pursuing.
Touches the following files:
----------------
M java/engine/org/apache/derby/iapi/services/property/PropertyUtil.java
The new method which hard-codes the analysis given on this JIRA. The code would
look a lot cleaner if we could switch on Strings, but that's not possible since
this class needs to compile on Java 6.
----------------
M java/engine/org/apache/derby/impl/sql/catalog/DataDictionaryImpl.java
M java/engine/org/apache/derby/impl/sql/catalog/DD_Version.java
M java/engine/org/apache/derby/catalog/SystemProcedures.java
Machinery (including upgrade logic) for adding the new system procedure.
----------------
M java/engine/org/apache/derby/loc/messages.xml
M java/shared/org/apache/derby/shared/common/reference/SQLState.java
A new error message, raised for unknown property names.
> Provide a way for users to determine the value of a Derby property
> ------------------------------------------------------------------
>
> Key: DERBY-6220
> URL: https://issues.apache.org/jira/browse/DERBY-6220
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 10.11.0.0
> Reporter: Rick Hillegas
> Attachments: derby-6220-01-aa-cleanupProperty.diff,
> derby-6220-01-aa-newSystemFunction.diff
>
>
> Derby properties can be specified as system properties, values stored in
> derby.properties, and values stored in the database via the
> syscs_set_database_property procedure. The rules for how these property sets
> interact are confusing. It would be good to provide users a way to figure out
> what Derby thinks a property is set to. Maybe we could provide a builtin or
> system function for this purpose.
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