MDEV-29345 update case insensitive (large) unique key with insensitiv…

…e change of value - duplicate key

use collation-sensitive comparison when comparing fields

mysql-test/main/long_unique_bugs.result

@@ -694,5 +694,27 @@ Hrecvx_0004ln-00	1
 Hrecvx_0004mm-00	2
 drop table t;
 #
-# End of 10.5 tests
+# MDEV-29345 update case insensitive (large) unique key with insensitive change of value - duplicate key
 #
+create table t1 (a int, b text, unique (b));
+insert ignore t1 values (1, 'a'), (2, 'A');
+Warnings:
+Warning	1062	Duplicate entry 'A' for key 'b'
+select * from t1;
+a	b
+1	a
+update t1 set b='A' where a=1;
+select * from t1;
+a	b
+1	A
+drop table t1;
+create table t1 (a int, b blob, unique (b));
+insert t1 values (1, 'a'), (2, 'A');
+select * from t1;
+a	b
+1	a
+2	A
+update t1 set b='A' where a=1;
+ERROR 23000: Duplicate entry 'A' for key 'b'
+drop table t1;
+# End of 10.5 tests

mysql-test/main/long_unique_bugs.test

@@ -671,5 +671,20 @@ insert into t values ('Hrecvx_0004mm-00',2)
 select * from t;
 drop table t;
 --echo #
---echo # End of 10.5 tests
+--echo # MDEV-29345 update case insensitive (large) unique key with insensitive change of value - duplicate key
 --echo #
+create table t1 (a int, b text, unique (b));
+insert ignore t1 values (1, 'a'), (2, 'A');
+select * from t1;
+update t1 set b='A' where a=1;
+select * from t1;
+drop table t1;
+
+create table t1 (a int, b blob, unique (b));
+insert t1 values (1, 'a'), (2, 'A');
+select * from t1;
+--error ER_DUP_ENTRY
+update t1 set b='A' where a=1;
+drop table t1;
+
+--echo # End of 10.5 tests

sql/handler.cc

@@ -7082,7 +7082,7 @@ int handler::check_duplicate_long_entries_update(const uchar *new_rec)
           So also check for that too
         */
         if((field->is_null(0) != field->is_null(reclength)) ||
-                               field->cmp_binary_offset(reclength))
+                               field->cmp_offset(reclength))
         {
           if((error= check_duplicate_long_entry_key(new_rec, i)))
             return error;