Postgresql explain analyze function

In order to measure the run-time cost of each node in the execution plan, the current implementation of EXPLAIN ANALYZE adds profiling overhead to query execution. As a result, running EXPLAIN ANALYZE on a query can sometimes take significantly longer than executing the query normally. The amount of overhead depends on the nature of the query. SQL explain analyse a function. I am trying to understand the query optimization in postgresql and I have a function with some queries in it.

Some of them are simple querys that saves a value into a variable and then the next query takes this variable to find something. Create a function to check execution. The EXPLAIN function shows how the tables involved in the statement will be scanned by index scanned or sequential scan, etc.

Try doing a PREPARE and then EXPLAIN EXECUTE , like. In extreme cases it can account for or more of query execution time. Just remember that EXPLAIN is a tool for measuring relative performance, and not absolute performance.

Important: Keep in mind that the statement is actually executed when ANALYZE is used. In some cases EXPLAIN ANALYZE provides additional execution statistics beyond the execution times and row counts, such as Sort and Hash above. This is one tool I will reach for every time I need to look at any database performance issues.

Statements inside plpgsql functions are considered nested statements. This is known as an execution plan and which is exposed by explain. Understanding this tells you how you can optimize your database with indexes to improve performance. The hard part for most users is understanding the output of these. You should be able to use auto- explain.

You might also want to set. During a non-timing performance testing phase, this output can be much more useful than EXPLAIN plans alone, as it provides what plan actually happened. The module provides no SQL-accessible functions. To use it, simply load it into the server. SELECT routine_name FROM information_schema.

The difference is that EXPLAIN shows you query cost based on collected statistics about your database, and EXPLAIN ANALYZE actually runs it to show the processed time for every stage. If I ran EXPLAIN ANALYZE f1(), I only get the total time, but no details. Is there a way I can get detailed for all queries in the function ? Stack Exchange network consists of 1QA communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Hello, I have strange problem.

But when I run query without EXPLAIN ANALYZE i get, for example: Time: 539. I get for example: Total runtime: 40. Query returns rows.

I do checks with psql connected using socket to postgresql server. I want this plan to be obfuscated before saving. PostgreSQL had to read more than 99.