select @test_compress_string:='string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa '; @test_compress_string:='string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa ' string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa select length(@test_compress_string); length(@test_compress_string) 117 select uncompress(compress(@test_compress_string)); uncompress(compress(@test_compress_string)) string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa select uncompress(@test_compress_string); uncompress(@test_compress_string) NULL Warnings: Error 1254 Too big size of uncompressed data. The maximum size is 8192. (probably, length of uncompressed data was corrupted) select uncompressed_length(compress(@test_compress_string))=length(@test_compress_string); uncompressed_length(compress(@test_compress_string))=length(@test_compress_string) 1 select uncompressed_length(compress(@test_compress_string)); uncompressed_length(compress(@test_compress_string)) 117 select length(compress(@test_compress_string))<length(@test_compress_string); length(compress(@test_compress_string))<length(@test_compress_string) 1 create table t1 (a text, b char(255), c char(4)) type=myisam; insert into t1 (a,b,c) values (compress(@test_compress_string),compress(@test_compress_string),'d '); select uncompress(a) from t1; uncompress(a) string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa select uncompress(b) from t1; uncompress(b) string for test compress function aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa select concat('|',c,'|') from t1; concat('|',c,'|') |d| drop table t1;