#1071 - Specified key was too long; max key length is 767 bytes

Question

I this SQL query to create a table:

CREATE TABLE IF NOT EXISTS `local_sysDB`.`hashtags` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `hashtag` VARCHAR(255) NOT NU         


        

Answer 1

"Hashes" are usually hex, not UTF-8. Hashes are usually much shorter than 255.

If either applies, then...

`hashtag`
       VARCHAR(160)           -- this
       CHARACTER SET ascii    -- and/or this

would be a solution that would work on any version without any of the innodb settings indicated.

(Note: 191 is the cutoff for VARCHAR with utf8mb4, but few standard hashes need that much.)

Answer 2

I just learned a workaround... Get 5.5.14 or 5.6.3 (or later), do the SETs indicated here, and use DYNAMIC or COMPRESSED:

SET GLOBAL innodb_file_per_table = ON,
           innodb_file_format = Barracuda,
           innodb_large_prefix = ON;
CREATE TABLE so29676724 (
  `id` INT NOT NULL AUTO_INCREMENT,
  `hashtag` VARCHAR(255) NOT NULL COMMENT 'hashtag must be unique. Must be saved without #',
   PRIMARY KEY (`id`),
  UNIQUE INDEX `hashtags_hashtag` (`hashtag` ASC)
)
ENGINE = InnoDB
DEFAULT CHARACTER SET  utf8mb4
ROW_FORMAT = COMPRESSED;

SHOW CREATE TABLE so29676724\G

mysql> CREATE TABLE so29676724 (
    ->   `id` INT NOT NULL AUTO_INCREMENT,
    ->   `hashtag` VARCHAR(255) NOT NULL COMMENT 'hashtag must be unique. Must be saved without #',
    ->    PRIMARY KEY (`id`),
    ->   UNIQUE INDEX `hashtags_hashtag` (`hashtag` ASC)
    -> )
    -> ENGINE = InnoDB
    -> DEFAULT CHARACTER SET  utf8mb4
    -> ROW_FORMAT = COMPRESSED;
Query OK, 0 rows affected (0.09 sec)