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  1. MariaDB Server
  2. MDEV-39843

prefix index causes incorrect range query result

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    • Q3/2026 Server Maintenance, Q4/2026 Server Maintenance

    Description

      The same SELECT statement returned different results after I dropped the index on the datatype LONGTEXT;

      DROP DATABASE IF EXISTS test;
      		 
      CREATE DATABASE test;
      		 
      USE test;
      		 
       
      		 
      CREATE TABLE `t0` (
      		 
      `c0` LONGTEXT,
      		 
      KEY `i0` (`c0`(1))
      		 
      ) ;
      		 
       
      		 
      INSERT INTO t0(c0) VALUES ('꙰dcF');
      		 
      REPLACE INTO t0(c0) VALUES ('kER');
      		 
       
      		 
      SELECT ALL t0.c0 FROM t0 WHERE 'C0' <= t0.c0; --{kER}
      		 
      DROP INDEX i0 ON t0;
      		 
      SELECT ALL t0.c0 FROM t0 WHERE 'C0' <= t0.c0; --{꙰dcF,kER}

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          relates to

          Bug - A problem which impairs or prevents the functions of the product. MDEV-40046 Range optimizer's const-bound folding mishandles numeric-overflow string literals (e.g. `'-1e500'`) on a prefix(1) index, producing "Impossible WHERE" and returning 0 rows where 12 are correct.

          • Major - Major loss of function.
          • Confirmed

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              raghunandan.bhat Raghunandan Bhat
              liufan liufan
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