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I am looking to compare indexes and further optimize my code. What I would like to do is force the query to run without an index so I can see what difference it has made. Is it possible to do this?
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SQL query will not automatically eliminate the duplicates , explicitily we have to use distinct keyword for removing duplicates from result set. If there is no indexes it will create index automatically. No two column can have the same name.
The USE INDEX ( index_list ) hint tells MySQL to use only one of the named indexes to find rows in the table. The alternative syntax IGNORE INDEX ( index_list ) tells MySQL to not use some particular index or indexes.
The symbol <> in MySQL is same as not equal to operator (!=). Both gives the result in boolean or tinyint(1). If the condition becomes true, then the result will be 1 otherwise 0.
The Benefits and Drawbacks of Using Indexes in MySQLIndexes consume disk space. Indexes degrade the performance of INSERT, UPDATE and DELETE queries – when data is updated, the index needs to be updated together with it. MySQL does not protect you from using multiple types of indexes at the same time.
Yes, you can ask the query to not use indexes by adding IGNORE INDEX (index1, index2, ...) to your query. More details can be found here.
Note: I know this is an old question and you would already have found the answer, but I hope this will help others looking for the same answer, and they wouldn't have to spend their valuable time digging through the MySQL docs.
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