On 7/21/2010 1:02 PM, Tompkins Neil wrote:
Hi
So Just running a basic query I get returned the following :
table,type,possible_keys,key,key_len,ref,rows,Extra,
Products,ALL,,,,,9884,where used,
Therefore, I assume "*ALL*" is the worst possible type and should look at
adding a an index to this particular field ?
Why assume when the manual is right there to remove all doubt?
http://dev.mysql.com/doc/refman/5.1/en/explain-output.html
####
ALL
A full table scan is done for each combination of rows from the previous
tables. This is normally not good if the table is the first table not
marked const, and usually very bad in all other cases. Normally, you can
avoid ALL by adding indexes that enable row retrieval from the table
based on constant values or column values from earlier tables.
####
--
Shawn Green
MySQL Principle Technical Support Engineer
Oracle USA, Inc.
Office: Blountville, TN
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