set @allowed_packet= @@max_allowed_packet; SET GLOBAL max_allowed_packet=67108864; connect con1, localhost, root,,; create table t1(a longblob unique, b longblob , c longblob , unique(b,c)); desc t1; Field Type Null Key Default Extra a longblob YES UNI NULL b longblob YES MUL NULL c longblob YES NULL show create table t1; Table Create Table t1 CREATE TABLE `t1` ( `a` longblob DEFAULT NULL, `b` longblob DEFAULT NULL, `c` longblob DEFAULT NULL, UNIQUE KEY `a` (`a`) USING HASH, UNIQUE KEY `b` (`b`,`c`) USING HASH ) ENGINE=MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci show keys from t1; Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment Ignored t1 0 a 1 a A NULL NULL NULL YES HASH NO t1 0 b 1 b A NULL NULL NULL YES HASH NO t1 0 b 2 c A NULL NULL NULL YES HASH NO insert into t1 values(concat(repeat('sachin',10000000),'1'),concat(repeat('sachin',10000000),'1'), concat(repeat('sachin',10000000),'1')); insert into t1 values(concat(repeat('sachin',10000000),'2'),concat(repeat('sachin',10000000),'2'), concat(repeat('sachin',10000000),'1')); insert into t1 values(concat(repeat('sachin',10000000),'2'),concat(repeat('sachin',10000000),'2'), concat(repeat('sachin',10000000),'4')); ERROR 23000: Duplicate entry 'sachinsachinsachinsachinsachinsachinsachinsachinsachinsachins...' for key 'a' insert into t1 values(concat(repeat('sachin',10000000),'3'),concat(repeat('sachin',10000000),'1'), concat(repeat('sachin',10000000),'1')); ERROR 23000: Duplicate entry 'sachinsachinsachinsachinsachinsachinsachinsachinsachinsachins...' for key 'b' drop table t1; disconnect con1; connection default; set @@GLOBAL.max_allowed_packet= @allowed_packet; # End of 10.4 tests