how can I increase the max key length?

[Sebastian Noack]

Hi,

if I try to install mediawiki, I get following mysql-error, during running
config/index.php: "Specified key was too long; max key length is 1000
bytes". How can I allow keys longer than 1000 bytes? I use mysql-4.1.14
from gentoo-portage.

Best regards
Sebastian Noack

[Christian Kirsch]

Sebastian Noack wrote:

> Hi,
>
> if I try to install mediawiki, I get following mysql-error, during running
> config/index.php: "Specified key was too long; max key length is 1000
> bytes". How can I allow keys longer than 1000 bytes? I use mysql-4.1.14
> from gentoo-portage.

Use the source, Luke.

Although I'd discourage using keys that long - what's the point? If you
need a key that is longer than 1000 bytes, it takes a lot of time to
figure out if a key matches a condition. If the keys are substrings of
blobs, there is not much point to it anyway. Unless you are storing
text, in which case a fulltext index would be appropriate.

[Sebastian Noack]

> Although I'd discourage using keys that long - what's the point? If you

> need a key that is longer than 1000 bytes, it takes a lot of time to
> figure out if a key matches a condition. If the keys are substrings of
> blobs, there is not much point to it anyway. Unless you are storing
> text, in which case a fulltext index would be appropriate.

Like I said, I only try to install mediawiki. But I have find out that the
following SQL-Query occurs the error:

CREATE TABLE categorylinks ( cl_from int(8) unsigned NOT NULL default '0',
cl_to varchar(255) binary NOT NULL default '', cl_sortkey varchar(255)
binary NOT NULL default '', cl_timestamp timestamp NOT NULL, UNIQUE KEY
cl_from(cl_from,cl_to), KEY cl_sortkey(cl_to,cl_sortkey(128)), KEY
cl_timestamp(cl_to,cl_timestamp) )

But because I don't have designed the db-structure by my own, I would
prefer to don't alter it. So I ask again, is there a way to increase the
max length for keys?

Best regards
Sebastian Noack

[Christian Kirsch]

Sebastian Noack wrote:

>>Although I'd discourage using keys that long - what's the point? If you
>>need a key that is longer than 1000 bytes, it takes a lot of time to
>>figure out if a key matches a condition. If the keys are substrings of
>>blobs, there is not much point to it anyway. Unless you are storing
>>text, in which case a fulltext index would be appropriate.

>
>
> Like I said, I only try to install mediawiki. But I have find out that the
> following SQL-Query occurs the error:
>
> CREATE TABLE categorylinks ( cl_from int(8) unsigned NOT NULL default '0',
> cl_to varchar(255) binary NOT NULL default '', cl_sortkey varchar(255)
> binary NOT NULL default '', cl_timestamp timestamp NOT NULL, UNIQUE KEY
> cl_from(cl_from,cl_to), KEY cl_sortkey(cl_to,cl_sortkey(128)), KEY
> cl_timestamp(cl_to,cl_timestamp) )
>
> But because I don't have designed the db-structure by my own, I would
> prefer to don't alter it. So I ask again, is there a way to increase the
> max length for keys?

Do you notice *any* key in this query that's longer than 255+128 = 383
bytes? I don't, but then I'm myopic. Maybe you could post the exact
error message?

[Unregistered]

Sebastian Noack wrote:

Do you notice *any* key in this query that's longer than 255+128 = 383
bytes? I don't, but then I'm myopic. Maybe you could post the exact
error message?

Multiply that by 3 since it's a UTF-8 database and you're over 1000 BYTES. It's been incredibly frustrating looking for a way to install programs, in my case Quartz, that _require_ tables with keys greater than 1000 bytes. It's so annoying when people "help" by being smart enough to tell us we shouldn't be using long keys, while being dumb enough not to actually read the question and notice that we have no choice!