How do you get the explain plan for a query in Oracle?

How do you get the explain plan for a query in Oracle?

Running EXPLAIN PLAN EXPLAIN PLAN FOR SELECT last_name FROM employees; This explains the plan into the PLAN_TABLE table. You can then select the execution plan from PLAN_TABLE . This is useful if you do not have any other plans in PLAN_TABLE , or if you only want to look at the last statement.

How do you analyze an explain plan?

How to Interpret an Explain Plan

1. Syntactic – checks the syntax of the query.
2. Semantic – checks that all objects exist and are accessible.
3. View Merging – rewrites query as join on base tables as opposed to using views.

How do I read a query plan in postgresql?

The easiest way to spot a node in query plan is where the arrows point to. Postgres will process the lowest level nodes first. In this case, it is the Bitmap Index Scan node to check condition unique1 < 10 on index tenk1_unique1. This node returns 10 rows.

How do you explain a plan in Toad?

How to Explain Plan in Toad?

1. In Toad, Open SQL editor by clicking on the menu Database > SQL Editor.
2. Then type your SQL query and press Ctrl+E to execute Explain Plan for that query.
3. If Plan Table does not exist in your database, then Toad will ask you to create a Plan Table.

How do I explain query in PostgreSQL?

The EXPLAIN statement returns the execution plan which PostgreSQL planner generates for a given statement. The EXPLAIN shows how tables involved in a statement will be scanned by index scan or sequential scan, etc., and if multiple tables are used, what kind of join algorithm will be used.

What is cardinality in explain plan?

Cardinality is the estimated number of rows the step will return. Cost is the estimated amount of work the plan will do. A higher cardinality => you’re going to fetch more rows => you’re going to do more work => the query will take longer.