mysql change innodb_large_prefix

Question

I just setup debian 8.3 on a VM and installed xampp after this Tutorial. Everything is working, until I tried to create a new table:

create table testtable
(
  id int(10) not null auto_increment,
  firstname varchar(255) collate utf8mb4_german2_ci not null,
  lastname varchar(255) collate utf8mb4_german2_ci not null,
  primary key (id),
  unique key (lastname)
)engine = innodb default charset=utf8mb4, collate=utf8mb4_german2_ci

I got the error: #1709 - Index column size too large. The maximum column size is 767 bytes. Then I found out this comes from the prefix limitation which is limited to 767Byte in Innodb and I can fix this by set the innodb_large_prefix in the my.cnf file. But I can't find the file, its not under /etc/ and theres no /etc/mysql/-folder, the only my.cnf I found is in /opt/lampp/etc/, however, after I added the innodb_large_prefix=1 to the file and restarted lampp. I stil get the same error. What did I do wrong?

edit: SELECT version() returns 5.6.14, so innodb_large_prefix should be supported.

edit2: I know I can work around this by only set part of the the key as index to get under 767Byte. But I want to know here how to config the mysql correctly.

Answer 1

Between 5.6.3 and 5.7.7 (that is if you are running MySQL 5.6 or MariaDB 10.0), there are 4 steps:

• SET GLOBAL innodb_file_format=Barracuda;
• SET GLOBAL innodb_file_per_table=ON;
• ROW_FORMAT=DYNAMIC; -- or COMPRESSED (goes on end of CREATE)
• innodb_large_prefix=1

Note

SELECT * FROM information_schema.INNODB_SYS_TABLESPACES;

will provide the file_format and row_format. Some other I_S tables provide clues of file_per_table.