How to troubleshoot and fix PostgreSQL performance issues

PostgreSQL database performance is critical for application performance. EzzEddin Abdullah shows how to get information about a query’s performance from the execution plan.…

25 May 2022 13 min read

Database Administration

Robert Sheldon in Database Administration

Retrieving SQL Server Query Execution Plans

Execution plans explain all you need to know about query performance, and how to fine-tune. Sure, you can see them in SSMS, but what if...

18 October 2016 26 min read

Dennes Torres

Optimizing Batch Process in SQL Server

SQL Server batch processes are usually run from SQL Agent in background. They can take significant time and resources, especially if they are ETL tasks....

08 May 2015 32 min read

Jonathan Lewis

Execution Plans Part 14: SQL Monitoring

This is the last part of my series on Execution plans, and features an option which is only available if you have licensed the Diagnostic...

26 March 2015 14 min read

Jonathan Lewis

Execution Plans Part 13: SQL Trace

In parts 11 and 12 of this series I described the “rowsource execution statistics” that we can collect as Oracle runs a query, then described...

11 March 2015 12 min read

Jonathan Lewis

Execution Plans Part 12: Cardinality Feedback

In the previous instalment of this series I introduced three ways of accessing the run-time statistics for a query and described, for one of the...

13 January 2015 13 min read

Grant Fritchey

Why Developers Need to Understand Execution Plans

As a coder, the more you know about the business, the better code you're going to write. The more you know about the language in...

12 January 2015 30 min read

Dennes Torres

Exploring Query Plans in SQL

SQL Server keeps the most-used execution plans in cache, so it doesn't need to recompile the same queries every time. How can we benefit from...

31 December 2014 15 min read

Jonathan Lewis

Execution Plans Part 11: Actuals

So far in this series we’ve talked about interpreting the shape of an execution plan and understanding the meaning of the predictions that the optimizer...

17 December 2014 13 min read

Jonathan Lewis

Execution Plans Part 10: Guesswork

In part 9 we saw an example of a simple nested loop join where the basic method for interpreting the numbers in an execution plan...

09 September 2014 9 min read

Jonathan Lewis

Execution Plans Part 9: Multiplication

In part 8 we looked at a very simple execution plan involving a hash join; but that example was too simple to give us the...

29 August 2014 7 min read

Jonathan Lewis

Execution Plans Part 8: Cost, time, etc.

It’s time to move away from the shape of an execution plan and turn our attention to some of the numerical information we get from...

19 August 2014 11 min read

Jonathan Lewis

Execution Plans Part 7: Query Blocks and Inline Views

When we examine an execution plan, we’re usually trying to work out the mechanical steps that Oracle took to produce a result set. When we...

09 July 2014 10 min read

Jonathan Lewis

Execution Plans Part 6: Pushed Subqueries

In part 5 of this series we examined a couple of examples where you had to handle the “first child first” rule with a little...

16 June 2014 10 min read

Jonathan Lewis

Execution Plans part 5: First Child Variations

I’ve offered up “first child first, recursive descent” as a basic strategy for interpreting execution plans – but it’s not a perfect rule, and it...

28 May 2014 14 min read

Jonathan Lewis

Execution Plans Part 4: Precision and Timing

In part 3 of this series we used a simple hash join to introduce the a simple guideline for reading execution plans – the “first...

14 May 2014 12 min read

Houri

SPM Plan: non reproducibility circumstances and CBO interaction

1. Introduction When a critical report which used to complete very quickly starts performing poorly, there is a big chance that the generic reason for...

01 May 2014 17 min read

Jonathan Lewis