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Query execution plan

Last modified: 11 October 2024

The EXPLAIN command shows the execution plan of a statement. It means you can see details on the approach that the planner took to execute the statement. For example, how the tables are scanned, what join algorithms are used to bring together the required rows, statement execution costs, and other information.

Execution cost is the planner's guess at how long it takes to run the statement. The measurement is made in relative cost units. The execution cost has two options: start-up and total. The start-up cost shows how long it takes before the first row can be processed, while the total cost shows how long it takes to process all the rows.

PyCharm supports two types of execution plans:

  • Explain Plan: the result is shown in a mixed tree and table format on a dedicated Plan tab.

  • Explain Plan (Raw): the result is shown in a table format.

If you use the ANALYZE option with EXPLAIN, the statement is actually executed, not only planned. In this case, you can see the run time statistics in milliseconds.