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Re: How to change max key length for MyISAM?


Dnia Thu, Jan 14, 2021 at 08:52:14PM +0100, Sergei Golubchik napisał(a):
> Hi, Witold!
> On Jan 14, Witold Filipczyk wrote:
> > > Why do you want to increase the max key length?
> > 
> > I like mysqlhotcopy as backup tool, but new soft requires big key.
> Yes, that's what I was asking. What does it require, can you show an
> example of a table definition?
> I mean, a non-unique key doesn't have to be that long. If it's smaller,
> it'll still help to narrow the search to all rows with the same
> 1000-byte prefix, and then just compare them all with the exact 3K
> value. So 1K-key will still help even if values are 3K (except when all
> your values have exactly the same 1K prefix, but it's not a very
> realistic scenario). But with 1K keys you'll fit 3 times more keys per
> index page, you'll have less disk IO, and less tree levels to search.
> You would really need 3K, if you have 3K UNIQUE key, for UNIQUE 3k
> contraints. Using 1K keys would change the semantics, values won't
> necessarily be unique anymore. But since 10.4 MariaDB supports unique
> constraints of arbitrary length. So, again, you should not need to
> increase max key length for that (except that you're on 10.3 now).

I'm trying to install prestashop- on MyISAM.

> Regards,
> Sergei
> VP of MariaDB Server Engineering
> and security@xxxxxxxxxxx

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