How is the usage of “oracle explain” explained?

“EXPLAIN” is a keyword in Oracle database used to retrieve detailed information about query execution plans. It is utilized to analyze the execution plan of a query statement, aiding developers in optimizing query performance. By using the “EXPLAIN” keyword, Oracle can provide detailed information about the query execution plan, including the indexes used in the query, the connection methods between tables, and the data access paths. This information helps developers understand how the query is executed, identify potential performance issues, and optimize as needed. The syntax for using the “EXPLAIN” keyword is as follows:

EXPLAIN PLAN FOR your_sql_statement

In this case, “your_sql_statement” is the query statement you want to analyze. After executing the statement above, the query execution plan will be saved in a special table in the database. You can retrieve detailed query execution plan information by querying this table. For example, you can use the following statement to query the execution plan:

SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY)

This will provide detailed information on the execution plan of the query, including query steps, access paths, join methods, etc. By analyzing the query execution plan, performance issues in the query can be identified and optimized as needed, such as creating appropriate indexes, rewriting query statements, adjusting parameters, etc., to improve query performance.