The EXPLAIN statement produces extra (“extended”) information that is not part of EXPLAIN output but can be viewed by issuing a SHOW WARNINGS statement following EXPLAIN . As of MySQL 8.0. 12, extended information is available for SELECT , DELETE , INSERT , REPLACE , and UPDATE statements.
What is extra column in MySQL explain?
The Extra column of EXPLAIN output contains additional information about how MySQL resolves the query. The following list explains the values that can appear in this column. Each item also indicates for JSON-formatted output which property displays the Extra value. For some of these, there is a specific property.
What does filtered mean?
1 : having unwanted elements (such as sediments) removed by means of a filter : subjected to filtration filtered water.
Which clause in MySQL indicates which columns to modify and the values they should be given while being used in update statement set Put get push?
The SET clause indicates which columns to modify and the values they should be given. The WHERE clause, if given, specifies which rows should be updated. Otherwise, all rows are updated.
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.
What is explain plan 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.
What is filtered column in MySQL explain?
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.
What is explain statement in MySQL?
The EXPLAIN statement provides information about how MySQL executes statements: EXPLAIN works with SELECT , DELETE , INSERT , REPLACE , and UPDATE statements. That is, MySQL explains how it would process the statement, including information about how tables are joined and in which order.
What is filtered in MySQL explain?
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. Before MySQL 5.7.
What is the purpose of filter?
A filter is a device or process that removes something from a signal. The complete or partial suppression of some aspect of the signal is the defining feature of filters.
Does explain Run query?
Warning: Adding ANALYZE to EXPLAIN will both run the query and provide statistics. This means that if you use EXPLAIN ANALYZE on a DROP command (Such as EXPLAIN ANALYZE DROP TABLE table), the specified values will be dropped after the query executes.
What does the filtered column in a mySQL table mean?
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.
What is the difference between rows and filtered columns?
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.
How does mymysql filter my data?
MySQL will first try to use an index, e.g. do a range scan on your table a using the search -key. It estimates to get 174 rows out of using that index, which is the number in rows. This step is not yet called filtering. After that, these 174 rows have to be checked against additional conditions (usually in your where -clause).
Is it possible to display extended output in MySQL by default?
Before MySQL 5.7.3, this column is displayed if you use EXPLAIN EXTENDED. As of MySQL 5.7.3, extended output is enabled by default and the EXTENDED keyword is unnecessary. I still don’t get it.
