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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-2967) Single character does not match high value unicode character with collation TERRITORY_BASED
Date Tue, 28 Aug 2007 19:41:30 GMT

    [ https://issues.apache.org/jira/browse/DERBY-2967?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12523324
] 

Mamta A. Satoor commented on DERBY-2967:
----------------------------------------

I do not have any numbers for the performance results for int array vs CollationElementIterator.
I searched Derby dev list and found few postings about how constructing an array before hand
may not be not necessary for a check which would fail within say first few characters. I also
found DERBY-2699 (performance of like in territory based collation databases may be improved
by changing way collation elements are calculated.) which also talks about the same issue
as your comment "One potential problem with the arrays is that the array is fully populated
even if the value could be disqualified on the first character, that would seem to degrade
performance, not improve it. " 

I will start investigating into using CollationElementIterator rather than an int array. This
will fix both this Jira entry and DERBY-2699 and possibly DERBY-2698.

If anyone has any comments please let me know.

> Single character does not match high value unicode character with collation TERRITORY_BASED
> -------------------------------------------------------------------------------------------
>
>                 Key: DERBY-2967
>                 URL: https://issues.apache.org/jira/browse/DERBY-2967
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.4.0.0
>            Reporter: Kathey Marsden
>         Attachments: TestFrench.java, TestNorway.java
>
>
> With TERRITORY_BASED collation '_' does not match  the character \uFA2D.  It is the same
for english or norwegian. FOR collation UCS_BASIC it matches fine.  Could you tell me if this
is a bug?
> Here is a program to reproduce.
> import java.sql.*;
> public class HighCharacter {
>    public static void main(String args[]) throws Exception
>    {
>    System.out.println("\n Territory no_NO");
>    Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
>    Connection conn = DriverManager.getConnection("jdbc:derby:nordb;create=true;territory=no_NO;collation=TERRITORY_BASED");
>    testLikeWithHighestValidCharacter(conn);
>    conn.close();
>    System.out.println("\n Territory en_US");
>    conn = DriverManager.getConnection("jdbc:derby:endb;create=true;territory=en_US;collation=TERRITORY_BASED");
>    testLikeWithHighestValidCharacter(conn);
>    conn.close();
>    System.out.println("\n Collation USC_BASIC");
>    conn = DriverManager.getConnection("jdbc:derby:basicdb;create=true");
>    testLikeWithHighestValidCharacter(conn);
>    }
> public static  void testLikeWithHighestValidCharacter(Connection conn) throws SQLException
{
>    Statement stmt = conn.createStatement();
>    try {
>    stmt.executeUpdate("drop table t1");
>    }catch (SQLException se)
>    {// drop failure ok.
>    }
>    stmt.executeUpdate("create table t1(c11 int)");
>    stmt.executeUpdate("insert into t1 values 1");
>  
>    // \uFA2D - the highest valid character according to
>    // Character.isDefined() of JDK 1.4;
>    PreparedStatement ps =
>    conn.prepareStatement("select 1 from t1 where '\uFA2D' like ?");
>      String[] match = { "%", "_", "\uFA2D" };
>    for (int i = 0; i < match.length; i++) {
>    System.out.println("select 1 from t1 where '\\uFA2D' like " + match[i]);
>    ps.setString(1, match[i]);
>    ResultSet rs = ps.executeQuery();
>    if( rs.next() && rs.getString(1).equals("1"))
>        System.out.println("PASS");
>    else          System.out.println("FAIL: no match");
>    rs.close();
>    }
>   }
> }
> Mamta made some comments on this issue in the following thread:
> http://www.nabble.com/Single-character-does-not-match-high-value-unicode-character-with-collation-TERRITORY_BASED.-Is-this-a-bug-tf4118767.html

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