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  1. MariaDB Server
  2. MDEV-30746

Regression in ucs2_general_mysql500_ci

Details

    Description

      ucs2_general_mysql500_ci is a MySQL-5.0.0 compatibility collations and (unlike ucs2_general_ci) sorts 'ß' after 's' in all MariaDB versions up to 10.3:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a VARCHAR(32) CHARACTER SET ucs2 COLLATE ucs2_general_mysql500_ci);
      		 
      INSERT INTO t1 VALUES ('s'),('z'),(_latin1 0xDF);
      		 
      SELECT GROUP_CONCAT(a) FROM t1 GROUP BY a ORDER BY a;


      +-----------------+
      		 
      | GROUP_CONCAT(a) |
      		 
      +-----------------+
      		 
      | s               |
      		 
      | z               |
      		 
      | ß               |
      		 
      +-----------------+

      Starting from 10.4 it returns a wrong result (equal to ucs2_general_ci):

      +-----------------+
      		 
      | GROUP_CONCAT(a) |
      		 
      +-----------------+
      		 
      | s,ß             |
      		 
      | z               |
      		 
      +-----------------+

      This is not expected. The compatibility collations should still provide the old MySQL-5.0.0 order.

      The order was broken by:

      commit a8efe7ab1f28e2219df5ae9aa88fa63c40ad1066
      		 
      Author: Alexander Barkov <bar@mariadb.com>
      		 
      Date:   Fri Oct 19 14:20:31 2018 +0400
      		 
       
      		 
          MDEV-17502 MDEV-17474 Change Unicode xxx_general_ci and xxx_bin collation implementation to "inline" style

      Note, a similar collation for utf8mb3 correctly returns results in the expected order in all MariaDB versions:

      DROP TABLE IF EXISTS t1;
      		 
      CREATE TABLE t1 (a VARCHAR(32) CHARACTER SET utf8mb3 COLLATE utf8mb3_general_mysql500_ci);
      		 
      INSERT INTO t1 VALUES ('s'),('z'),(_latin1 0xDF);
      		 
      SELECT GROUP_CONCAT(a) FROM t1 GROUP BY a ORDER BY a;


      +-----------------+
      		 
      | GROUP_CONCAT(a) |
      		 
      +-----------------+
      		 
      | s               |
      		 
      | z               |
      		 
      | ß               |
      		 
      +-----------------+

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        Issue Links

          blocks

          Bug - A problem which impairs or prevents the functions of the product. MDEV-30577 Case folding for uca1400 collations is not up to date

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

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              bar Alexander Barkov
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                Updated:
                Resolved:

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