if a key length exceeds the supported maximum and it is safe to auto-decrease it, do it.

include/my_global.h

@@ -382,8 +382,8 @@ typedef unsigned short ushort;
 #define sgn(a)		(((a) < 0) ? -1 : ((a) > 0) ? 1 : 0)
 #define swap(t,a,b)	{ register t dummy; dummy = a; a = b; b = dummy; }
 #define test(a)		((a) ? 1 : 0)
-#define set_if_bigger(a,b)  { if ((a) < (b)) (a)=(b); }
-#define set_if_smaller(a,b) { if ((a) > (b)) (a)=(b); }
+#define set_if_bigger(a,b)  do { if ((a) < (b)) (a)=(b); } while(0)
+#define set_if_smaller(a,b) do { if ((a) > (b)) (a)=(b); } while(0)
 #define test_all_bits(a,b) (((a) & (b)) == (b))
 #define set_bits(type, bit_count) (sizeof(type)*8 <= (bit_count) ? ~(type) 0 : ((((type) 1) << (bit_count)) - (type) 1))
 #define array_elements(A) ((uint) (sizeof(A)/sizeof(A[0])))

mysql-test/r/ctype_utf8.result

@@ -168,4 +168,4 @@ hex(s1)
 41
 drop table t1;
 create table t1 (a char(160) character set utf8, primary key(a));
-ERROR HY000: Incorrect sub part key. The used key part isn't a string, the used length is longer than the key part or the storage engine doesn't support unique sub keys
+ERROR 42000: Specified key was too long; max key length is 255 bytes

mysql-test/r/myisam.result

@@ -323,10 +323,10 @@ Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 drop table t1;
 CREATE TABLE t1 (a varchar(255), b varchar(255), c varchar(255), KEY t1 (a, b, c));
-ERROR 42000: Specified key was too long. Max key length is 500
+ERROR 42000: Specified key was too long; max key length is 500 bytes
 CREATE TABLE t1 (a varchar(255), b varchar(255), c varchar(255));
 ALTER TABLE t1 ADD INDEX t1 (a, b, c);
-ERROR 42000: Specified key was too long. Max key length is 500
+ERROR 42000: Specified key was too long; max key length is 500 bytes
 DROP TABLE t1;
 CREATE TABLE t1 (a int not null, b int, c int, key(b), key(c), key(a,b), key(c,a));
 INSERT into t1 values (0, null, 0), (0, null, 1), (0, null, 2), (0, null,3), (1,1,4);

mysql-test/r/type_blob.result

@@ -346,9 +346,17 @@ HELLO MY	1
 a	1
 hello	1
 drop table t1;
+create table t1 (a text, unique (a(300)));
+ERROR 42000: Specified key was too long; max key length is 255 bytes
 create table t1 (a text, key (a(300)));
-ERROR HY000: Incorrect sub part key. The used key part isn't a string, the used length is longer than the key part or the storage engine doesn't support unique sub keys
-create table t1 (a text, key (a(255)));
+Warnings:
+Warning	1071	Specified key was too long; max key length is 255 bytes
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `a` text,
+  KEY `a` (`a`(255))
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
 CREATE TABLE t1 (
 t1_id bigint(21) NOT NULL auto_increment,

mysql-test/t/ctype_utf8.test

@@ -103,5 +103,5 @@ drop table t1;
 # Bug 2699
 # UTF8 breaks primary keys for cols > 85 characters
 #
---error 1089
+--error 1071
 create table t1 (a char(160) character set utf8, primary key(a));

mysql-test/t/type_blob.test

@@ -121,8 +121,10 @@ select c,count(*) from t1 group by c;
 select d,count(*) from t1 group by d;
 drop table t1;
 
-!$1089 create table t1 (a text, key (a(300))); # should give an error
-create table t1 (a text, key (a(255)));
+-- error 1071
+create table t1 (a text, unique (a(300))); # should give an error
+create table t1 (a text, key (a(300)));    # key is auto-truncated
+show create table t1;
 drop table t1;
 
 #

sql/share/english/errmsg.txt

@@ -72,9 +72,9 @@ character-set=latin1
 "Not unique table/alias: '%-.64s'",
 "Invalid default value for '%-.64s'",
 "Multiple primary key defined",
-"Too many keys specified. Max %d keys allowed",
+"Too many keys specified; max %d keys allowed",
 "Too many key parts specified. Max %d parts allowed",
-"Specified key was too long. Max key length is %d",
+"Specified key was too long; max key length is %d bytes",
 "Key column '%-.64s' doesn't exist in table",
 "BLOB column '%-.64s' can't be used in key specification with the used table type",
 "Too big column length for column '%-.64s' (max = %d). Use BLOB instead",

sql/share/russian/errmsg.txt

@@ -76,7 +76,7 @@ character-set=koi8r
 "   ",
 "   .     %d ",
 "     .     %d ",
-"   .     %d",
+"   .     %d ",
 "  '%-.64s'    ",
 "  BLOB '%-.64s'           ",
 "    '%-.64s' ( = %d).   BLOB  ",

sql/share/ukrainian/errmsg.txt

@@ -79,7 +79,7 @@ character-set=koi8u
 "   ",
 " ަ .   ¦ %d ަ",
 "   .   ¦ %d ",
-"  . ¦   %d",
+"  . ¦   %d Ԧ",
 "  '%-.64s'  դ  æ",
 "BLOB  '%-.64s'      Φ    Ц æ",
 "   '%-.64s' (max = %d).   BLOB",

sql/sql_table.cc

@@ -850,26 +850,35 @@ int mysql_create_table(THD *thd,const char *db, const char *table_name,
 	{
 	  if ((length=column->length) > file->max_key_length() ||
 	      length > file->max_key_part_length())
-	  {
-	    my_error(ER_WRONG_SUB_KEY,MYF(0));
-	    DBUG_RETURN(-1);
-	  }
-	}
-        /* TODO HF What's this for??? */
-	else if (f_is_geom(sql_field->pack_flag))
-	{
-	}
-	else if (column->length > length ||
-		 ((f_is_packed(sql_field->pack_flag) ||
-		   ((file->table_flags() & HA_NO_PREFIX_CHAR_KEYS) &&
-		    (key_info->flags & HA_NOSAME))) &&
-		  column->length != length))
-	{
-	  my_error(ER_WRONG_SUB_KEY,MYF(0));
-	  DBUG_RETURN(-1);
+          {
+            length=min(file->max_key_length(), file->max_key_part_length());
+            if (key->type == Key::MULTIPLE)
+            {
+              /* not a critical problem */
+              char warn_buff[MYSQL_ERRMSG_SIZE];
+              sprintf(warn_buff,ER(ER_TOO_LONG_KEY),length);
+              push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
+                           ER_TOO_LONG_KEY, warn_buff);
+            }
+            else
+            {
+              my_error(ER_TOO_LONG_KEY,MYF(0),length);
+              DBUG_RETURN(-1);
+            }
+          }
 	}
-	if (!(file->table_flags() & HA_NO_PREFIX_CHAR_KEYS))
-	  length=column->length;
+	else if (!f_is_geom(sql_field->pack_flag) &&
+                  (column->length > length ||
+                   ((f_is_packed(sql_field->pack_flag) ||
+                     ((file->table_flags() & HA_NO_PREFIX_CHAR_KEYS) &&
+                      (key_info->flags & HA_NOSAME))) &&
+                    column->length != length)))
+        {
+          my_error(ER_WRONG_SUB_KEY,MYF(0));
+          DBUG_RETURN(-1);
+        }
+        else if (!(file->table_flags() & HA_NO_PREFIX_CHAR_KEYS))
+          length=column->length;
       }
       else if (length == 0)
       {
@@ -879,8 +888,20 @@ int mysql_create_table(THD *thd,const char *db, const char *table_name,
       }
       if (length > file->max_key_part_length())
       {
-	my_error(ER_WRONG_SUB_KEY,MYF(0));
-	DBUG_RETURN(-1);
+        length=file->max_key_part_length();
+        if (key->type == Key::MULTIPLE)
+        {
+          /* not a critical problem */
+          char warn_buff[MYSQL_ERRMSG_SIZE];
+          sprintf(warn_buff,ER(ER_TOO_LONG_KEY),length);
+          push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
+                       ER_TOO_LONG_KEY, warn_buff);
+        }
+        else
+        {
+          my_error(ER_TOO_LONG_KEY,MYF(0),length);
+          DBUG_RETURN(-1);
+        }
       }
       key_part_info->length=(uint16) length;
       /* Use packed keys for long strings on the first column */