I have following problem:

Create Table is:
CREATE TABLE search_keyword (
id int(11) NOT NULL COMMENT ‘ID’,
keyword varchar(60) NOT NULL,
search_result text,

In field “search_result” I have compressed a lot of data with:
update search_keyword set search_result = COMPRESS(search_result)

…and now, when I try to access this data with

select UNCOMPRESS(search_result) from search_keyword where keyword = …

I get NULL as result. Why???

In the documentation I saw a remark, that only binary fields are recommended

"(However, use of nonbinary string data types such as CHAR or VARCHAR to store compressed strings is not recommended anyway because character set conversion may occur. Use a VARBINARY or BLOB binary string column instead.) "

In this case I had not binary field. Is this a reason for this problem? Is there a way to get data back? html#function_uncompress

As long as you use the same collation everywhere, text should not pose a problem.