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https://issues.apache.org/jira/browse/DERBY-2335?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12496130
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Mamta A. Satoor commented on DERBY-2335:
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Mike, I was planning of doing the javadoc fix and removing the redundant method
in BaseTypeCompiler as part of my cleanup. Didn't realize I accidentally
included 2 imports. I will take care of that too and see if anything else needs
cleanup.
As for including impl reference in iapi, I am not too sure about the rules
here. The advantage of using ExpressionClassBuilder is that the reference to
the method descriptor can be hold on to because it is for per generated class
level.
The junit tests have passed fine with this patch and I am running derbyall
right now. I will go ahead and cleanup the code and check it in. If there is
further concern about impl and iapi boundaries, we can take it up as a
subsequent discussion/patch.
> Compare character datatypes with different collation ordering.
> --------------------------------------------------------------
>
> Key: DERBY-2335
> URL: https://issues.apache.org/jira/browse/DERBY-2335
> Project: Derby
> Issue Type: Sub-task
> Components: SQL
> Affects Versions: 10.3.0.0
> Reporter: Mamta A. Satoor
> Assigned To: Mamta A. Satoor
> Attachments:
> DERBY2335_correct_collation_for_constants_persistent_column_v1_diff.txt,
> DERBY2335_correct_collation_for_constants_persistent_column_v1_stat.txt,
> DERBY2335_fix_stringCompare_Method_CollatorSQLxxx_classes_v1_diff.txt,
> DERBY2335_fix_stringCompare_Method_CollatorSQLxxx_classes_v1_stat.txt,
> DERBY2335_More_tests_And_Fix_getNull_v1_diff.txt,
> DERBY2335_More_tests_And_Fix_getNull_v1_stat.txt,
> DERBY2335_Use_LCC_in_ValueNode_v1_diff.txt,
> DERBY2335_Use_LCC_in_ValueNode_v1_stat.txt,
> DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v1_diff.txt,
> DERBY2335_Use_PushDataValueFactory_in_ExpressionClassBuilder_v1_stat.txt
>
>
> The parent task DERBY-1478 will enable users to have a different collation
> order for user-defined character datatypes compared to UNICODE based
> collation, UCS_BASIC, used by system tables. This sub-task is added to handle
> the case where a comparison is made between character datatypes with
> different collation order.
> For instance
> Let's say, a database is created to use a territory based collation for
> character types. And say there is a userSchema schema in that database which
> has a table tableInfo with column tablename defined as VARCHAR. This
> tableInfo.tablename will have territory based collation assoicated with it.
> And say this column is then compared with a VARCHAR column in SYS schema,
> then how will the comparison happen, since the 2 columns being compared have
> different collation associated with them?
> select * from sys.systables and userSchema.tableInfo where
> systables.tablename = tableInfo,tablename
> Thanks to Rick for taking the time out on this issue. He had following
> suggestion
> </Rick comment start>
> "As I read part 2 of the SQL Standard, it looks like you need a CAST in order
> to compare 2 strings which have different collations bound to them. Both
> string operands must have the same collation--that is my reading of Syntax
> rule 3b in section 9.13. Sections 6.12 and 6.1 explain how to cast the
> operands so that you can compare them. I think you need to write an
> expression like this:
> WHERE userStringCol = CAST ( systemStringCol AS VARCHAR COLLATE
> userStringColumnsCollation )
> Here's an example I googled up:
> http://docs.openlinksw.com/virtuoso/sqlrefDATATYPES.html. Hope this helps.
> </Rick comment end>
> When this task is taken up, it would be good to explore Rick's suggestion.
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