#1071 - Specified key was too long; max key length is 1000 bytes

Question

I know questions with this title have been answered before, but please do read on. I've read thoroughly all the other questions/answers on this error before posting.

I am getting the above error for the following query:

CREATE TABLE IF NOT EXISTS `pds_core_menu_items` (
  `menu_id` varchar(32) NOT NULL,
  `parent_menu_id` int(32) unsigned DEFAULT NULL,
  `menu_name` varchar(255) DEFAULT NULL,
  `menu_link` varchar(255) DEFAULT NULL,
  `plugin` varchar(255) DEFAULT NULL,
  `menu_type` int(1) DEFAULT NULL,
  `extend` varchar(255) DEFAULT NULL,
  `new_window` int(1) DEFAULT NULL,
  `rank` int(100) DEFAULT NULL,
  `hide` int(1) DEFAULT NULL,
  `template_id` int(32) unsigned DEFAULT NULL,
  `alias` varchar(255) DEFAULT NULL,
  `layout` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`menu_id`),
  KEY `index` (`parent_menu_id`,`menu_link`,`plugin`,`alias`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Does anyone have idea why and how to fix it? The catch is - this same query works perfectly on my local machine, and worked as well on my previous host. Btw.it's from a mature project - phpdevshell - so I'd guess these guys know what they are doing, although you never know.

Any clue appreciated.

I'm using phpMyAdmin.

Answer 1

I had this error and I made another indexing command for the userEmail in a separate command;

CREATE INDEX users_index_v1 ON users (admin,testingAccount,deleted,userEmail,fname,lname, country);
ERROR 1071 (42000): Specified key was too long; max key length is 1000 bytes

i just remove userEmail from first statement and retype it separately :

CREATE INDEX users_index_email ON users (userEmail);

Answer 2

See three kinds of solutions of this error here or follow this as well

Getting the same exception while running back-end application in this case we can set out engine "InnoDb" set GLOBAL storage_engine='InnoDb';

if the above configuration is not working for you then change your key length for example if it is by default selected 255 char you can change it below of 100 Example - create table role ( role_name varchar(99) not null, role_description varchar(255), primary key (role_name)); it is works for me

Answer 3

I was facing the same issue; used the below query to resolve it.

While creating the DB you can use utf-8 encoding.

eg. create database my_db character set utf8 collate utf8mb4;

EDIT:

(Considering suggestions from comments)

Changed utf8_bin to utf8mb4

Answer 4

I have gone through so many tricks, but none worked for me. Then I found the best and simplest one:

If you are working with mysql-workbench, while altering index select (Engine:)-innoDb.

Answer 5

If the sql is not created yourself, maybe just check and set the length of column to usual length.

Answer 6

Well , I just changed from MyISAM to InnoDB like this

Before changing

ENGINE=MyISAM DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

After changing

ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

Answer 7

if you are using Laravel 7 or Laravel 8, goto to config/database.php

'engine' => 'innoDb',

that should work especially using Wamp or Xampp.

Answer 8

I had this error and I changed my tables column length smaller for the indexed foreign key columns so I changed it like this:

VARCHAR(1024)

To:

VARCHAR(512)

And run the query again.

Answer 9

I had this issue, and solved by following:

Cause

There is a known bug with MySQL related to MyISAM, the UTF8 character set and indexes that you can check here.

Resolution

• Make sure MySQL is configured with the InnoDB storage engine.

• Change the storage engine used by default so that new tables will always be created appropriately:

  set GLOBAL storage_engine='InnoDb';

• For MySQL 5.6 and later, use the following:

  SET GLOBAL default_storage_engine = 'InnoDB';

• And finally make sure that you're following the instructions provided in Migrating to MySQL.

Reference

Answer 10

As @Devart says, the total length of your index is too long.

The short answer is that you shouldn't be indexing such long VARCHAR columns anyway, because the index will be very bulky and inefficient.

The best practice is to use prefix indexes so you're only indexing a left substring of the data. Most of your data will be a lot shorter than 255 characters anyway.

You can declare a prefix length per column as you define the index. For example:

...
KEY `index` (`parent_menu_id`,`menu_link`(50),`plugin`(50),`alias`(50))
...

But what's the best prefix length for a given column? Here's a method to find out:

SELECT
 ROUND(SUM(LENGTH(`menu_link`)<10)*100/COUNT(`menu_link`),2) AS pct_length_10,
 ROUND(SUM(LENGTH(`menu_link`)<20)*100/COUNT(`menu_link`),2) AS pct_length_20,
 ROUND(SUM(LENGTH(`menu_link`)<50)*100/COUNT(`menu_link`),2) AS pct_length_50,
 ROUND(SUM(LENGTH(`menu_link`)<100)*100/COUNT(`menu_link`),2) AS pct_length_100
FROM `pds_core_menu_items`;

It tells you the proportion of rows that have no more than a given string length in the menu_link column. You might see output like this:

+---------------+---------------+---------------+----------------+
| pct_length_10 | pct_length_20 | pct_length_50 | pct_length_100 |
+---------------+---------------+---------------+----------------+
|         21.78 |         80.20 |        100.00 |         100.00 |
+---------------+---------------+---------------+----------------+

This tells you that 80% of your strings are less than 20 characters, and all of your strings are less than 50 characters. So there's no need to index more than a prefix length of 50, and certainly no need to index the full length of 255 characters.

PS: The INT(1) and INT(32) data types indicates another misunderstanding about MySQL. The numeric argument has no effect related to storage or the range of values allowed for the column. INT is always 4 bytes, and it always allows values from -2147483648 to 2147483647. The numeric argument is about padding values during display, which has no effect unless you use the ZEROFILL option.

Answer 11

I have just made bypass this error by just changing the values of the "length" in the original database to the total of around "1000" by changing its structure, and then exporting the same, to the server. :)

Answer 12

run this query before creating or altering table.

SET @@global.innodb_large_prefix = 1;

this will set max key length to 3072 bytes

Answer 13

This index size limit seems to be larger on 64 bit builds of MySQL.

I was hitting this limitation trying to dump our dev database and load it on a local VMWare virt. Finally I realized that the remote dev server was 64 bit and I had created a 32 bit virt. I just created a 64 bit virt and I was able to load the database locally.

Answer 14

This error means that length of index index is more then 1000 bytes. MySQL and storage engines may have this restriction. I have got similar error on MySQL 5.5 - 'Specified key was too long; max key length is 3072 bytes' when ran this script:

CREATE TABLE IF NOT EXISTS test_table1 (
  column1 varchar(500) NOT NULL,
  column2 varchar(500) NOT NULL,
  column3 varchar(500) NOT NULL,
  column4 varchar(500) NOT NULL,
  column5 varchar(500) NOT NULL,
  column6 varchar(500) NOT NULL,
  KEY `index` (column1, column2, column3, column4, column5, column6)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

UTF8 is multi-bytes, and key length is calculated in this way - 500 * 3 * 6 = 9000 bytes.

But note, next query works!

CREATE TABLE IF NOT EXISTS test_table1 (
  column1 varchar(500) NOT NULL,
  column2 varchar(500) NOT NULL,
  column3 varchar(500) NOT NULL,
  column4 varchar(500) NOT NULL,
  column5 varchar(500) NOT NULL,
  column6 varchar(500) NOT NULL,
  KEY `index` (column1, column2, column3, column4, column5, column6)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

...because I used CHARSET=latin1, in this case key length is 500 * 6 = 3000 bytes.