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Asked by: Odette Jungkunz
technology and computing databasesWhat is the use of explain in MySQL?
Last Updated: 2nd April, 2020
The EXPLAIN keyword is used throughout various SQL databases and provides information about how your SQL database executes a query. In MySQL, EXPLAIN can be used in front of a query beginning with SELECT , INSERT , DELETE , REPLACE , and UPDATE .
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In this manner, what is explain in MySQL?
The EXPLAIN statement provides information about how MySQL executes statements: EXPLAIN works with SELECT , DELETE , INSERT , REPLACE , and UPDATE statements. When EXPLAIN is used with an explainable statement, MySQL displays information from the optimizer about the statement execution plan.
Subsequently, question is, how do you use explain? The verb explain is not followed by object pronoun. It can't be followed by a pronoun like me, him, her, you or us that is the object of the verb, or the pronoun that receives the action of the verb. That's why “Can you explain me …?” is wrong. The verb explain has a very specific sentence pattern.
Besides, what is Key_len in MySQL explain?
mysql. According to MySQL website, 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.
What is filtered in explain MySQL?
As described here in the MySQL docs: The filtered column indicates an estimated percentage of table rows that will be filtered by the table condition. That is, rows shows the estimated number of rows examined and rows × filtered / 100 shows the number of rows that will be joined with previous tables. As of MySQL 5.7.