Bug #2821 Table default character set affects LONGBLOB fields

mysql-test/r/alter_table.result

@@ -343,6 +343,22 @@ t1	CREATE TABLE `t1` (
   `a` char(10) character set latin1 default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=cp1251
 drop table t1;
+create table t1 (myblob longblob,mytext longtext) 
+default charset latin1 collate latin1_general_cs;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `myblob` longblob,
+  `mytext` longtext character set latin1 collate latin1_general_cs
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+alter table t1 character set latin2;
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `myblob` longblob,
+  `mytext` longtext character set latin2
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
 CREATE TABLE t1 (
 Host varchar(16) binary NOT NULL default '',
 User varchar(16) binary NOT NULL default '',

mysql-test/t/alter_table.test

@@ -183,6 +183,17 @@ show create table t1;
 
 drop table t1;
 
+#
+# Bug#2821
+# Test that table CHARACTER SET does not affect blobs
+#
+create table t1 (myblob longblob,mytext longtext) 
+default charset latin1 collate latin1_general_cs;
+show create table t1;
+alter table t1 character set latin2;
+show create table t1;
+drop table t1;
+
 #
 # Test ALTER TABLE ENABLE/DISABLE keys when things are locked
 #

sql/sql_table.cc

@@ -470,9 +470,11 @@ int mysql_create_table(THD *thd,const char *db, const char *table_name,
       sql_field->charset= create_info->default_table_charset;
     /*
       table_charset is set in ALTER TABLE if we want change character set
-      for all varchar/char columns
+      for all varchar/char columns.
+      But the table charset must not affect the BLOB fields, so don't
+      allow to change my_charset_bin to somethig else.
     */
-    if (create_info->table_charset)
+    if (create_info->table_charset && sql_field->charset != &my_charset_bin)
       sql_field->charset= create_info->table_charset;
     sql_field->create_length_to_internal_length();