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Re: Optimize - Using Temp, Using Filesort, Group By Having
Posted by: Rick James ()
Date: April 19, 2011 10:40PM

767 comes from the 255 in VARCHAR, times 3 for utf8. It is not necessarily "wrong". It is bulky if you don't need it.

It is good to have utf8 as the default throughout the database. But if you are storing a hex number, SSN, post code, part number, ip address, etc., then it makes more sense to declare it ascii and/or limit it to a realistic size. Certain indexing, sorting, filtering, etc, things can benefit somewhat.

utf8 is an encoding that stores English as 1-byte characters; European languages as 1-, sometimes 2-byte characters, Most Asian languages as 3-byte characters. Still, there are some internal operations where MySQL pre-allocates 3 bytes per character, regardless of what the text is.

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Subject Views Written By Posted
Optimize - Using Temp, Using Filesort, Group By Having 3450 Lenny Dunn 04/08/2011 10:40AM
Re: Optimize - Using Temp, Using Filesort, Group By Having 1148 Rick James 04/09/2011 11:37PM
Re: Optimize - Using Temp, Using Filesort, Group By Having 884 Lenny Dunn 04/12/2011 01:38PM
Re: Optimize - Using Temp, Using Filesort, Group By Having 1455 Rick James 04/13/2011 07:56AM
Re: Optimize - Using Temp, Using Filesort, Group By Having 833 Lenny Dunn 04/13/2011 09:44AM
Re: Optimize - Using Temp, Using Filesort, Group By Having 1463 Rick James 04/14/2011 12:08AM
Re: Optimize - Using Temp, Using Filesort, Group By Having 1318 Lenny Dunn 04/19/2011 12:18PM
Re: Optimize - Using Temp, Using Filesort, Group By Having 776 Rick James 04/19/2011 10:40PM


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