MySQL Error: Key Specification Without a Key Length

MySQL error: key specification without a key length

The error happens because MySQL can index only the first N chars of a BLOB or TEXT column. So The error mainly happens when there is a field/column type of TEXT or BLOB or those belong to TEXT or BLOB types such as TINYBLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, MEDIUMTEXT, and LONGTEXT that you try to make a primary key or index. With full BLOB or TEXT without the length value, MySQL is unable to guarantee the uniqueness of the column as it’s of variable and dynamic size. So, when using BLOB or TEXT types as an index, the value of N must be supplied so that MySQL can determine the key length. However, MySQL doesn’t support a key length limit on TEXT or BLOB. TEXT(88) simply won’t work.

The error will also pop up when you try to convert a table column from non-TEXT and non-BLOB type such as VARCHAR and ENUM into TEXT or BLOB type, with the column already been defined as unique constraints or index. The Alter Table SQL command will fail.

The solution to the problem is to remove the TEXT or BLOB column from the index or unique constraint or set another field as primary key. If you can't do that, and wanting to place a limit on the TEXT or BLOB column, try to use VARCHAR type and place a limit of length on it. By default, VARCHAR is limited to a maximum of 255 characters and its limit must be specified implicitly within a bracket right after its declaration, i.e VARCHAR(200) will limit it to 200 characters long only.

Sometimes, even though you don’t use TEXT or BLOB related type in your table, the Error 1170 may also appear. It happens in a situation such as when you specify VARCHAR column as primary key, but wrongly set its length or characters size. VARCHAR can only accepts up to 256 characters, so anything such as VARCHAR(512) will force MySQL to auto-convert the VARCHAR(512) to a SMALLTEXT datatype, which subsequently fails with error 1170 on key length if the column is used as primary key or unique or non-unique index. To solve this problem, specify a figure less than 256 as the size for VARCHAR field.

Reference: MySQL Error 1170 (42000): BLOB/TEXT Column Used in Key Specification Without a Key Length

mysql - used in key specification without a key length

You can not define index by TEXT / BLOB columns without specifying index length:

BLOB and TEXT columns also can be indexed, but a prefix length must be
given.

Logically - that is because these data types represent huge data and, therefore, index can not be created by whole field.

BLOB/TEXT column 'bestilling' used in key specification without a key length

you can't set a text as a primary key. Mysql only can Index some characters, and type text could be too big to index.

take a look here:

• http://www.mydigitallife.info/mysql-error-1170-42000-blobtext-column-used-in-key-specification-without-a-key-length/

• MySQL error: key specification without a key length

BLOB/TEXT column 'value' used in key specification without a key length

Looks like this is the issue (having the same issue right now), these two lines:

INDEX `IDX_ALPHANUM_INFO_TEXT_ATTRIBUTE_ID_VALUE` (`attribute_id`, `value`),
INDEX `IDX_ALPHANUM_INFO_TEXT_ENTITY_TYPE_ID_VALUE` (`entity_type_id`, `value`),

Need to have numerical values listed as such:

INDEX `IDX_ALPHANUM_INFO_TEXT_ATTRIBUTE_ID_VALUE` (`attribute_id`, `value`(255)),
INDEX `IDX_ALPHANUM_INFO_TEXT_ENTITY_TYPE_ID_VALUE` (`entity_type_id`, `value`(255)),

Plug that in, and it will work. The trick is getting it to insert correctly. For brevity's sake I won't post the whole function, but in Mage_Eav_Model_Entity_Setup::createEntityTables at about line 1341, you need to modify these lines:

            ->addIndex($this->getIdxName($eavTableName, array('attribute_id', 'value')),
                array('attribute_id', 'value'))
            ->addIndex($this->getIdxName($eavTableName, array('entity_type_id', 'value')),
                array('entity_type_id', 'value'))

As follows:

            ->addIndex($this->getIdxName($eavTableName, array('attribute_id', 'value')),
                array('attribute_id', $type == 'text' ? array('name' => 'value', 'size' => 255) : 'value'))
            ->addIndex($this->getIdxName($eavTableName, array('entity_type_id', 'value')),
                array('entity_type_id', $type == 'text' ? array('name' => 'value', 'size' => 255) : 'value'))

I'm not quite sure what you should set the size value to, but I would think that setting it to the full 64k would defeat the purpose of indexing in the first place. Hopefully someone that knows a little bit more about sql than I will chime in.

Hope that helps.

1170 - BLOB/TEXT column 'XXX' used in key specification without a key length

long is probably not the type you think it is. You probably want bigint:

CREATE TABLE `ContentRepository`.`无标题`  (
  `weng_id` bigint NOT NULL,
  `content_type` tinyint(0) NOT NULL DEFAULT 0,
   . . .
)

long is a large string (mediumtext). It is not suitable for indexing in general.

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