Re: Unclear about key_len in EXPLAIN output
At 11:09 am -0500 3/2/06, sheeri kritzer wrote: >The manual is large and vast, I couldn't find the text you quoted on >the page I sent. What page did you find that text on? It's the latter part of the second sentence from the same paragraph that you quoted in your e-mail. >As well, if the key that EXPLAIN uses is multi-part, you would know >from the length of the fields. You have to use some deductive >reasoning, but I don't think it's really murky*shrug* If you have a key combined from different integer column types and text columns then it's not very clear what the relationship between a multi-part key and key_len is. From what the manual says I initially assumed that key_len simply represented the number off key parts used. I don't think a manual suffers from things being spelt out more clearly! James Harvard -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: Unclear about key_len in EXPLAIN output
The manual is large and vast, I couldn't find the text you quoted on the page I sent. What page did you find that text on? As well, if the key that EXPLAIN uses is multi-part, you would know from the length of the fields. You have to use some deductive reasoning, but I don't think it's really murky*shrug* -Sheeri On 2/2/06, James Harvard <[EMAIL PROTECTED]> wrote: > 'That other statement' that I quoted is actually just part of the paragraph > from the manual that you quoted! > > My point was that it doesn't say what units the key length is given in or > explain _how_ to determine the number of parts used. However the more I think > about it the more I see that it must be bytes, and I have posted a comment to > that effect on the manual page. > > James > > At 10:58 am -0500 2/2/06, sheeri kritzer wrote: > >according to: > >http://dev.mysql.com/doc/refman/5.0/en/explain.html > > > >"The key_len column indicates the length of the key that MySQL decided > >to use. The length is NULL if the key column says NULL. Note that the > >value of key_len enables you to determine how many parts of a > >multiple-part key MySQL actually uses." > > > >there are special exceptions to that for index_merge and range join types. > > > >The manual agrees; you are correct; it's the length of the key. Where > >did you find that other statement? It might be the index_merge join > >type's key_len... > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: Unclear about key_len in EXPLAIN output
'That other statement' that I quoted is actually just part of the paragraph from the manual that you quoted! My point was that it doesn't say what units the key length is given in or explain _how_ to determine the number of parts used. However the more I think about it the more I see that it must be bytes, and I have posted a comment to that effect on the manual page. James At 10:58 am -0500 2/2/06, sheeri kritzer wrote: >according to: >http://dev.mysql.com/doc/refman/5.0/en/explain.html > >"The key_len column indicates the length of the key that MySQL decided >to use. The length is NULL if the key column says NULL. Note that the >value of key_len enables you to determine how many parts of a >multiple-part key MySQL actually uses." > >there are special exceptions to that for index_merge and range join types. > >The manual agrees; you are correct; it's the length of the key. Where >did you find that other statement? It might be the index_merge join >type's key_len... -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Re: Unclear about key_len in EXPLAIN output
according to: http://dev.mysql.com/doc/refman/5.0/en/explain.html "The key_len column indicates the length of the key that MySQL decided to use. The length is NULL if the key column says NULL. Note that the value of key_len enables you to determine how many parts of a multiple-part key MySQL actually uses." there are special exceptions to that for index_merge and range join types. The manual agrees; you are correct; it's the length of the key. Where did you find that other statement? It might be the index_merge join type's key_len... Sincerely, Sheeri On 2/1/06, James Harvard <[EMAIL PROTECTED]> wrote: > According to the manual "the value of key_len enables you to determine how > many parts of a multiple-part key MySQL actually uses." > > However, it doesn't specify quite how one can determine that. It _looks_ like > the number of bytes in the key (or key part) that is used - is that correct? > > TIA, > James Harvard > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED] > > -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
Unclear about key_len in EXPLAIN output
According to the manual "the value of key_len enables you to determine how many parts of a multiple-part key MySQL actually uses." However, it doesn't specify quite how one can determine that. It _looks_ like the number of bytes in the key (or key part) that is used - is that correct? TIA, James Harvard -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe:http://lists.mysql.com/[EMAIL PROTECTED]
