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From "TomohitoNakayama" <tomon...@basil.ocn.ne.jp>
Subject Re: Derby-134, indexes and sorting locale-sensitive / case insensitive
Date Fri, 22 Apr 2005 16:33:15 GMT
Hello.

I have implemented the patch for Derby-134, which you mentioned.
The solution for Derby-134 in that patch was just only enabling use of 
expression like as "UPPER(text_val)" in order clause.

As in next URL mentioned, index with expression is not supported yet, and I 
did'nt make it support in that patch.
Only Simple-column-Name is supported.
http://incubator.apache.org/derby/manuals/reference/sqlj27.html#HDRSII-SQLJ-20937

//I feel there exists request for index with expression...

Then, if you want benefit of index,
you would need to prepare column which have value for sorting , and sort by 
the column for sorting in sql,   in application program layer.

Best regards.

/*

         Tomohito Nakayama
         tomonaka@basil.ocn.ne.jp
         tomohito@rose.zero.ad.jp

         Naka
         http://www5.ocn.ne.jp/~tomohito/TopPage.html

*/
----- Original Message ----- 
From: "Joerg von Frantzius" <joerg.von.frantzius@artnology.com>
To: <derby-dev@db.apache.org>
Cc: <derby-user@db.apache.org>
Sent: Friday, April 22, 2005 5:12 PM
Subject: Derby-134, indexes and sorting locale-sensitive / case insensitive


> Hi,
>
> there had been a long discussion of Derby-134 ("Sorted string columns are 
> sorted in a case sensitive way"), which in the end looked to me as being 
> solved, i.e. someone has supplied a "good-looking" patch. Now is there any 
> chance of a binary build coming up in the near future, where this patch 
> would be included?
>
> Talking about "ORDER BY", after reading the manuals about optimization and 
> in particular 
> http://incubator.apache.org/derby/manuals/tuning/perf45.html#Cost-Based+ORDER+BY+Sort+Avoidance
> I'm still not sure about a few things. My problem is that I have a GUI 
> with a table widget that displays >1500 rows, and I want to make use of 
> Derby's index structures to have fast column sorting. Maybe that simply 
> won't help here, because I need the ordering to be both locale-sensitive 
> and case-insensitive.
>
> With an ascending index on a VARCHAR column:
> 1. does that index default to case-insensitive ordering of the column?
> 2. does it maintain the ordering  in a locale-sensitive way, e.g. by using 
> java.text.Collator? (e.g. using the default locale active at index 
> creation time)
> 3. will "ORDER BY ... DESCENDING" make use of the index by simply 
> reversing its order, or will it result in full re-sorting with 
> performance-penalty?
>
> Thanks for any information,
> Jörg.
>
>
>
>
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> 



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