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From Daniel John Debrunner <...@apache.org>
Subject Re: svn commit: r561514 - /db/derby/code/trunk/java/engine/org/apache/derby/iapi/types/DataTypeDescriptor.java
Date Tue, 31 Jul 2007 21:03:35 GMT
mamta@apache.org wrote:
> Author: mamta
> Date: Tue Jul 31 13:48:39 2007
> New Revision: 561514
> 
> URL: http://svn.apache.org/viewvc?view=rev&rev=561514
> Log:
> Adding comment to the function that was added for DERBY-2793
> 
> 
> Modified:
>     db/derby/code/trunk/java/engine/org/apache/derby/iapi/types/DataTypeDescriptor.java
> 
> Modified: db/derby/code/trunk/java/engine/org/apache/derby/iapi/types/DataTypeDescriptor.java
> URL: http://svn.apache.org/viewvc/db/derby/code/trunk/java/engine/org/apache/derby/iapi/types/DataTypeDescriptor.java?view=diff&rev=561514&r1=561513&r2=561514
> ==============================================================================
> --- db/derby/code/trunk/java/engine/org/apache/derby/iapi/types/DataTypeDescriptor.java
(original)
> +++ db/derby/code/trunk/java/engine/org/apache/derby/iapi/types/DataTypeDescriptor.java
Tue Jul 31 13:48:39 2007
> @@ -1155,6 +1155,25 @@
>  		return false;
>  	}
>  	
> +	/**
> +	 * Compare the collation info on this DTD with the passed DTD. The rules
> +	 * are as follows
> +	 * 1)If both the DTDs have collation derivation of NONE, then they can't be
> +	 * compared and we return false.
> +	 * 2)If both the DTDs have same collation derivation (which in Derby's case
> +	 * at this point will mean collation derivation of IMPLICIT), then check
> +	 * the collation types. If they match, then return true. If they do not 
> +	 * match, then they can't be compared and hence return false.
> +	 * 
> +	 * In future, when we do support collation derivation of EXPLICIT, we will
> +	 * need to change this method so that we follow the correct SQL standard
> +	 * rules about what should happen if one collation derivation is EXPLICIT
> +	 * and other is NONE/IMPLICIT.

Isn't it true that even without supporting EXPLICT that algorithm in the 
method is a subset of the SQL standard? IMPLICIT,NONE should succeed, 
but will fail with this algorithm.

Dan.


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