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Do you want to know why a PostgreSQL query is slow? Then EXPLAIN ANALYZE is a great starting point. But query plans can depend on other server activity, can take a while to run, and can change over time, so if you want to see the actual execution plans of your slowest queries, auto_explain is the tool you need. In this post, we’ll look into what it does, how to configure it, and how to use those logs to speed up your queries. What is auto_explain? auto_explain is a PostgreSQL extension that allows you to log the query plans for queries slower than a (configurable) threshold. This is incredibly useful for debugging slow queries, especially those that are only sometimes problematic. It is one of the contribution modules, so can be installed and configured easily on regular PostgreSQL, and is so useful that we have it on by default on ScaleGrid. Huge thanks to Takahiro Itagaki, the main author behind the first version of auto_explain ( , ), Dean Rasheed, whose it was based on, and the many contributors and reviewers to it since. commit thread initial patch and suggestion Which auto_explain parameters should I use? Below we’ll discuss the most important parameters, but please do review the table below, or the , for more information on the full array of things you can track. official documentation The most important parameter for auto_explain is log_min_duration. By default this is set to -1, which means nothing will be logged – so if we want some logs we need to change it! The default unit is ms, so a setting of 100 will log the query plans for all queries that exceed 100ms. This is what we chose as default in ScaleGrid, but it can be configured under Admin -> Config. If, for some reason, you want to log the query plan for every query, you can set this to 0 – but beware, this can have severe performance implications. Since the queries are already being executed on the server, you probably also want to enable auto_explain.log_analyze. This makes the output equivalent to running EXPLAIN ANALYZE. By default, it also means that per-operation timings are tracked. This comes with some additional overhead, which can be minimised by turning off auto_explain.log_timing (on by default with log_analyze). Naturally though, per-operation timings are very useful when debugging slow queries! Our internal testing showed acceptable overheads for this, so it is on by default in ScaleGrid, but as ever please test your workload to see if the overhead is acceptable in your case. There is currently limited publicly available information on this topic, but a recent post by the ​​pgMustard team showed that, at least on a small transactional workload, . As they noted, this could be reduced with the auto_explain.sample_rate parameter, at the cost of only tracking a subset of your queries. the overhead can be as low as 2% The final parameter we’ll discuss in a bit of detail is auto_explain.log_format. The default output is TEXT, which is likely what you’re most familiar with from using EXPLAIN. Here is a simple example of what auto_explain output in TEXT format can look like: 2021-09-10 15:32:04.606 BST [22770] LOG:  duration: 3184.383 ms  plan: Query Text: select * from table1 order by column1; Sort  (cost=12875.92..13125.92 rows=100000 width=37) (actual time=2703.799..3055.401 rows=100000 loops=1) Sort Key: column1 Sort Method: external merge  Disk: 4696kB Buffers: shared hit=837, temp read=587 written=589 ->  Seq Scan on table  (cost=0.00..1834.01 rows=100000 width=37) (actual time=0.033..27.795 rows=100000 loops=1) Buffers: shared hit=834 You can see here that you get the query duration at the beginning, which you may be used to seeing at the end of query plans usually. You’ll also see the query text, including any parameters. The popular visualisation tools and both accept query plans in TEXT format, but they also both support JSON format. If some of your team prefer to use tools like and , that only support the JSON format, you might wish to set that as the format. For customers on ScaleGrid we opted for the JSON format, partly as we wanted to parse it more easily for our own slow query analysis feature. explain.depesz explain.dalibo PEV pgMustard Here is a full list of the auto_explain parameters, and their defaults: PostgreSQL defaults | Parameter | ScaleGrid defaults -1 auto_explain.log_min_duration | | 100 Off auto_explain.log_analyze | | On On (with log_analyze) auto_explain.log_timing | | On Off auto_explain.log_buffers | | On Off auto_explain.log_verbose | | On Off auto_explain.log_triggers | | Off Off auto_explain.log_nested_statements | | Off Off auto_explain.log_settings (v12) | | Off Off auto_explain.log_wal (v13) | | Off TEXT auto_explain.log_format | | JSON LOG auto_explain.log_level | | LOG a 1 uto_explain.sample_rate | | 1 Installing auto_explain On ScaleGrid, auto_explain is on by default, with a threshold of 100ms. You can configure this under Admin -> Config. On vanilla PostgreSQL, you can install auto_explain simply by adding it to one of session_preload_libraries or shared_preload_libraries. The former has the advantages of a) not requiring a restart (but it’ll only be loaded in new sessions) and b) making it possible to enable it only for some users (by setting this parameter with ALTER ROLE SET). As such, a basic config set-up for auto_explain could look like this: session_preload_libraries = auto_explain auto_explain.log_min_duration = 100 auto_explain.log_analyze = true auto_explain.log_buffers = true auto_explain.log_format = JSON If you’re using a different hosting provider, it’s worth checking whether they support auto_explain. For example, RDS Postgres does, but unlike ScaleGrid, it is off by default, so you’ll need to edit the configuration to get it running. Loading auto_explain into a single session If you don’t want auto_explain running in sessions automatically, as a superuser you also have the option of loading it into a single session: LOAD 'auto_explain'; This can be incredibly useful for one-off debugging sessions but naturally is unnecessary if you are able to have it running already. auto_explain limitations and gotchas We have mentioned some of these in passing already, but it seems a sensible time to remind ourselves of some of the downsides and limitations of auto_explain. Firstly, especially when tracking per-operation timings, there can be measurable overhead to using auto_explain. It can be low, even with timings being measured, but as ever it’s worth doing your own testing. Secondly, auto_explain timings are exclusive of query planning time. Planning time is often tiny on slow queries, but in exceptional cases, it can be responsible for the majority of the issue. As such, bear in mind that these cases may not show in your logs, or if they do, a discrepancy with what you’re seeing in total latency might be to do with the planning time. A manual EXPLAIN ANALYZE will quickly help you spot this. How to use the explain output to speed up queries Once you have the explain output for your slowest queries, you can now start looking into speeding them up! You’ll need to get the query plans out of the logs, which you can use for if you’re not using a managed service that does this for you. pgBadger Reviewing EXPLAIN plans is a huge topic in its own right. The PostgreSQL documentation includes a , and Thoughbot’s article on is a good next step. If you’d prefer an hour-long talk, by Josh Berkus was excellent. For more information, Depesz has a series of posts called and the pgMustard team have a fairly comprehensive . good but brief introduction to using EXPLAIN reading EXPLAIN ANALYZE EXPLAIN Explained Explaining the unexplainable EXPLAIN Glossary If you need help from PostgreSQL experts to manage your databases and speed up your slow queries, give ScaleGrid a try. We provide free 24/7 enterprise-level support that can guide you through these slow queries and help you get them all optimized. Our gives you plenty of time to try out our many features for and our other supported databases. free 30-day trial PostgreSQL We hope this gives you everything you need to get started with auto_explain and start speeding up any slow queries you have. If there’s anything else you’d like to know, do get in touch.

Log Slow Postgres Query Plans Automatically: An Introduction to auto-explain

Let's refresh Our CSS Grid Memory. Here's a Cheat Sheet of everything you can do with Grid to get started in 2021!🎖️ Check Out The YouTube Tutorial Here Grid Architecture grid-template-columns This is used to define the of columns. You can either individually set the width of each column, or set a uniform width for all columns using "repeat()" function. Number & Width grid-template-rows This is used to define the of rows. You can either individually set the height of each row, or set a uniform height for all rows using "repeat()" function. Number & Height grid-template-areas This is used to specify the amount of space a grid cell should carry in terms of column & row across the parent container. Life's quite easier with this as it allows us to see visually what we're doing. Call it, the blueprint(template) of our layout👇 column-gap This property is used to place gap between inside the grid 👇 Columns row-gap This property is used to place gap between inside the grid 👇 Rows justify-items This is used to position grid-items (children) inside the grid container along the . The values are 👇 X-Axis[Main Axis] 4 align-items This is used to position grid-items (children) inside grid container along the . The values are 👇 Y-Axis[Cross Axis] 4 justify-content This is used to position our grid [Basically everything] inside grid container along the . The values are 👇 X-Axis[Main Axis] 7 align-content This is used to position our grid [Basically everything] inside the grid container along the . The values are 👇 Y-Axis[Cross Axis] 7 Children Properties The Grid Scale grid-column : start/end THESE 2 properties are used to join multiple together. It is a shorthand of & Skip to this topic on the video above if you're confused using the timestamps. COLUMNS grid-column-start grid-column-end grid-row : start/end THESE 2 properties are used to join multiple together. It is a shorthand of & ROWS grid-row-start grid-row-end grid-area At first, we need to setup ☝️ Once done, we have to specify the names used in parent class inside the children classes, like this👇 grid-template-areas Specifying grid-template-areas inside parent container 👇 Specifying the names used in parent container inside children classes with grid-areas👇 Justify-self This is used to position grid-item (children) inside grid container along the . The values are 👇 1 individual X-Axis[Main Axis] 4 align-self This is used to position grid-item (children) inside grid container along the . The are 👇 1 individual Y-Axis[Cross Axis] 4 values Short Hands place-content place-items place-self grid-template gap/grid-gap Article Credits Conclusion Here's Your Medal For reading till the end ❤️ Suggestions & Criticisms Are Highly Appreciated ❤️ Be sure to check out my other channels and profiles: YouTube/ Joy Shaheb Twitter / JoyShaheb Instagram / JoyShaheb

The Ultimate CSS Grid Cheat Sheet in 2021🎖️

93 Stories To Learn About QA (Quality Assurance) 

Let's learn about via these 41 free stories. They are ordered by most time reading created on HackerNoon. Visit the to find the most read stories about any technology. Test Driven Development /Learn Repo trial and errors are key to building anything new and innovative. 1. Why You Need to Stop Writing Unit Tests The way you test has a huge impact on your codebase maintainability. There is  a simple way to improve it 2. Test Driven Development (TDD): Killing Bugs Before Day Zero Here's why you need to know TDD craft. 3. 5 Ways to Prevent Server Hardware Failure Use mature tools to make mature software 4. Test-driven Development: How to Write Unit Tests Tests are a way to explicitly set expectations about code. You establish them to allow the machine to check whether your code meets the expectations. 5. Best Practices to Write Unit Tests the Right Way In this article we will review some best practices and must-have libraries which will get your unit tests to the next level. 6. Just Enough Testing: How Many Automated Tests Should We Write? How many automated tests should you write? Just Enough. Just Enough Testing balances the need to ship with the quality your customers deserve. 7. TDD Conference 2021: Opening Ceremony by Alex Bunardzic Alex is a software engineering veteran with over 30 years of hands-on professional experience. He is a staunch advocate of Extreme Programming and TDD. 8. Best Practices to Write Unit Tests the Right Way (Part 2) All you need to know about unit testing LINQ and mappings in .NET to make more reliable code faster as you develop software using systems like AutoMapper 9. Build a CLI App with Oclif and Node.js Using Test-Driven Development: Part 2 TDD for building a CLI application using the oclif framework. 10. Why I Don't Think TDD Is Essential Test Driven Development puts emphasis on unit over integration tests. The result can be lower quality featuring bugs that are baked into the product. 11. A Closer Look at the Most Used Tools for Software Testing Using automation testing tools is an excellent way to go about verification of your product. 12. Choosing Test Cases for Automation That Can Increase Your ROI In this article, we will explore the key considerations when choosing test cases for Automation Testing. 13. Wordles, Centaur and Code: Building a Game The Conquest and Conquer is an analogy for serious software development. I will combine the TDD solution with an automated code generated using Artificial Intel 14. Test Your APIs in an Easy Way By Using Python Module PyHTTPTest I've struggled and spent a lot of hours writing manual Python scripts to be able to test a product involving many microservices. All of them following the REST conventions. Overwhelmed with too many scripts, each one test different endpoints, how they respond also what they respond, I've decided to create a Python package to easily do this, without needing to create a manual Python script, import libraries to send an HTTP Request, copy and paste code from other scripts to test fast the new endpoints, etc. 15. Unit Testing Made Easier With Pure Functions By getting used to unit tests, they can start to familiarize themselves with the codebase and make significant progress while facing no risk or stress. 16. Build a CLI App with Oclif and Node.js Using Test-Driven Development While writing a CLI tool can be a lot of fun, the initial setup and boilerplate—parsing arguments and flags, validation, subcommands—is generally the same. 17. How To Adopt TDD In Your Team This is the first in a series of blog posts in which we outline the benefits of TDD for your organization and what are the projects to consider while adopting this agile process. Link of Part Two. 18. Using the Software Testing Maturity Model to Refine Your Testing Strategy Want to improve your software quality engineering processes but don't know where to start? This software testing maturity model and assessment may help! 19. Road to Simplicity: Tests Are Not Tests [Part Two] This is the second story of Road to Simplicity. And it’s about the role of tests in software writing. 20. Creating a Wordle with TDD in Javascript We keep practicing this amazing Kata and learning. You can follow the steps! 21. We Should Get Rid of "Hello, World!" Forever💩 Every tutorial I've read for the last 30 years starts with the infamous 'Hello World' example. This could be one of the reasons we write crappy software. 22. Dependency Injection to Make Your Code Testable [A How-To Guide] Have you ever wanted to write unit tests for your code, but you’ve found that it’s difficult to do so? Often this is the result of not writing code with testing in mind. An easy way to solve this is through utilizing test-driven development, a development process in which you write your tests before your app code. 23. An Example of True Test Driven Development in Vue In true TDD, tests must fail, tests must pass, and the code must be refactored. 24. The Complex Relationship Between Software Developers and Test Code I was preparing yet another session about Test Driven Development (TDD) (I do quite a lot of these as part of my position) and I thought it would be a good idea to allure the audience at the beginning by showing some statistics. 25. Developers Should Drive Their E2E Tests to Cypress All software companies strive to produce quality products. The journey begins with a product that works. Software correctness is usually defined as the adherence of software to its specification. In most cases, formal verification is not possible. As such, we typically impose functional correctness with test coverage. 26. Don't Get Bitten by Hidden Bugs: Test Driven Development (TDD) and AAA Testing via xUnit Test Driven Development (TDD) is a software development cycle that focusses on describing the behaviour of your code first using tests 27. The Untold Truth of Test Driven Development Your Practical Introduction to Test Driven Development 28. Why Software Testing is So Important It isn't about being diligent.  It's because we've forgotten what we knew. 29. Software Development is Not About Unit Tests Photo by ShareGrid on Unsplash 30. Effective Testing in Complex Software Development Projects Manual Or Automatic Testing? 31. Writing Software from the Outside In Whenever you’re developing software, a certain amount of refactoring and rewriting is inevitable. This is sometimes due to a new idea that will simplify the design or a change to the project requirements. But unfortunately, it often also happens because of a misunderstanding about how the software will connect and interact with its external environment. While it’s impossible to completely avoid such miscommunication, you can minimize it by using a principle I call writing software from the outside in. 32. Test-Driven Development with RSpec in Rails When we start developing an app we usually do it the old fashion way: we get an idea, we elaborate on it, we make a plan to develop an app then we start coding and in the end, we test if our app is working properly. 33. Behavior-Driven Development From Scratch [101] Behavior-Driven Development (BDD) is a really powerful tool that helps us build robust, value-based software. You can sometimes hear detractors say that it brings a lot of complexity and leads to long tests difficult to maintain. Let's take stock of what BDD really is, by determining anti-patterns and best practices. 34. Test-Driven Development is Fundamentally Wrong It sounds backwards because it really is 35. How to Write Tests for React - Part 1 [Beginner's Guide] Writing React Test with react recommended libraries — Jest & React Testing Library for complete beginners. 36. Building a Wordle Game Using Test-Driven Development in 25 Minutes Developing a complete word game is very easy with TDD 37. How to Use RSpec From Basics to Testing User Input On my journey on Microverse, one of the things that troubled me the most to understand was RSpec, a Ruby gem for Test-Driven Development. The concept is quite simple. You create tests as you code along, so in the future, if an update breaks something, it will be easy to notice because one or more tests will fail. 38. An Introduction to Test-Driven Development Test-driven development (TDD) is all the rage these days and has been a discussion topic for quite some time. If you are brand new to TDD, this article should serve as a good introduction to what TDD is, why it’s useful, what a typical TDD workflow looks like, and when to use TDD. 39. How to Squeeze Test Driven Development on Legacy Systems We all love T.D.D. We know its benefits, we have read a thousand tutorials on how to build a system using this technique. But this not feasible for currently legacy systems. 40. 6 Lessons I Learned with Software Testing For the last few of months I started digging into the software testing world. I really wanted to learn more about how to create more effective tests, refactor code with more confidence and feel safe about adding new features. However, I felt it is little difficult to dive right in this area, that in my point of view, is underestimated. 41. Zombie Testing: One Behavior at a Time Selecting great test cases is very hard. Unless you summon the undead. Thank you for checking out the 41 most read stories about Test Driven Development on HackerNoon. to find the most read stories about any technology. Visit the /Learn Repo

41 Stories To Learn About Test Driven Development

341 Stories To Learn About Testing

Let's learn about via these 40 free stories. They are ordered by most time reading created on HackerNoon. Visit the to find the most read stories about any technology. Tdd /Learn Repo 1. Test Driven Development (TDD): Killing Bugs Before Day Zero Here's why you need to know TDD craft. 2. Property-Based Testing: The Diamond Kata, First and Last Line Content Intro 3. How Good Are We At Writing Tests? This is some thoughts about TDD and how things don't always work out perfectly even with the best-written tests when developing new software on a deadline. 4. How to Use binding.pry to Debug a Rails Application in a Docker Container Debugging in a docker container isn't that straightforward. At least it is not in the way my team set everything up. I will describe my methods for debugging. 5. I Pushed my Code to the Master Branch Without Tests Until I stumbled upon TDD, I had never really understood tests. I remember writing a whole project without tests and publishing it. Can you believe it? 6. How To Make A Record of Selenium Test Selenium is a open-source free and automation testing tool for web applications across all different browsers. It is quite similar as HP QuickTest Pro (QTP, currently UFT). However, Selenium mainly focused on automating web-based applications. So the testing done using Selenium tool is referred as Selenium Testing. In order to record a test, follow the given steps:
Step 1 : Open Mozilla Firefox web browser, go to tools and click on Selenium IDE. There type the link 7. Best Practices to Write Unit Tests the Right Way In this article we will review some best practices and must-have libraries which will get your unit tests to the next level. 8. Python Cheatsheet: Mock Object Library Python's simplicity permeates it all, and tests are not an exception. I left behind -temporarily- my JUnit and Mockito days by pytest and unittest. 9. Fast Prototyping With Azure Functions and TDD I Had an Idea 10. Why I Don't Think TDD Is Essential Test Driven Development puts emphasis on unit over integration tests. The result can be lower quality featuring bugs that are baked into the product. 11. How to Effectively Apply TDD in Enterprise Application Development Methodology to enable fast development of robust enterprise applications applying Test-Driven Development (TDD) and Hexagonal Architecture. 12. Building A Test Runner in Jest - A How-To Guide I use Jest nearly every day when working, and it's a fantastic tool. It lets me ship my code with confidence, knowing that I have produced something which works as intended. 13. The Untold Truth of Test Driven Development Your Practical Introduction to Test Driven Development 14. How 'displayName' Helps In Testing React Using Styled Components How to get rid of the weird styled component names in test snapshots 15. Introduction To Property-Based Testing in C# Intro 16. Testing in C#: Property-Based Testing With Input Generators Intro 17. Fully Covering .NET C# Console Application With Unit Tests Best Practice Cover DotNet (.NET) CSharp (C#) with unit tests with Test Driven Development TDD Dependency Injection DI Inversion of Control IoC Containers 18. Avoiding the Pitfalls of Unit Test High Code Coverage With TDD High unit test code coverage is often viewed as a key indicator of code quality, but it's important to focus on the quality of the unit tests, not just the cod 19. Wordles, Centaur and Code: Building a Game The Conquest and Conquer is an analogy for serious software development. I will combine the TDD solution with an automated code generated using Artificial Intel 20. Software Development is Not About Unit Tests Photo by ShareGrid on Unsplash 21. TDD Conference 2021: Opening Ceremony by Alex Bunardzic Alex is a software engineering veteran with over 30 years of hands-on professional experience. He is a staunch advocate of Extreme Programming and TDD. 22. Building a Wordle Game Using Test-Driven Development in 25 Minutes Developing a complete word game is very easy with TDD 23. Building a To-do List App with Python: Data Access Layer with SQLAlchemy If you ever used an ORM, you already know that it can save a lot of time, especially when starting a project, but as the codebase grows it can become impossible 24. Do Not Refactor Code That is Not Yet Working: Beautiful Code is Working Code Excessive concern about the beauty of the source code can compromise the outcome of a project. 25. Refactor: You Keep Using That Word… I stumbled upon a thread recently where the question was posed, “What are some common mistakes when refactoring code?” 26. Test-Driven Development with RSpec in Rails When we start developing an app we usually do it the old fashion way: we get an idea, we elaborate on it, we make a plan to develop an app then we start coding and in the end, we test if our app is working properly. 27. Why Software Testing is So Important It isn't about being diligent.  It's because we've forgotten what we knew. 28. Testimonial Driven Development Build your products based on the testimonials you want to get from your customers 29. Test-Driven Development is Fundamentally Wrong It sounds backwards because it really is 30. Never Make Assumptions: 5 Golden Rules for Web App Development No matter if you are a startup company or a big enterprise, your app needs to be intuitive and customer-facing to win many hearts. However, designing a user-friendly web app for your business is not so easy. You need to be aware of the complete rules. 31. Creating a Wordle with TDD in Javascript We keep practicing this amazing Kata and learning. You can follow the steps! 32. Testing Asynchronous JS Code: 2020 Edition The text you are about to read describes an imaginary dialog between two programmers on their way to discover the orgastic pleasures of a library called asyncFn. 33. Conditional Coin Flips with Rock Paper Scissors In the recent sweltering world heat wave, I was set a tech test the other day. In it I needed to write a function that would output zero to five depending on its 6 combinations. For this example I’ll say we wanna get the outcome of flipping a coin and playing rock, paper, scissors translated into a number ranging from 0 to 5. 34. A Guide to Code Kata with SRFI-64 I got into the habit of doing about 30 minutes of Code Kata every morning. I practice these Kata following the test-driven development (TDD) approach. 35. Don't Get Bitten by Hidden Bugs: Test Driven Development (TDD) and AAA Testing via xUnit Test Driven Development (TDD) is a software development cycle that focusses on describing the behaviour of your code first using tests 36. How to Build Awesome Integration Tests with Capybara Tips that would help you build integration tests using RSpec and Capybara. 37. An Introduction to Test-Driven Development Test-driven development (TDD) is all the rage these days and has been a discussion topic for quite some time. If you are brand new to TDD, this article should serve as a good introduction to what TDD is, why it’s useful, what a typical TDD workflow looks like, and when to use TDD. 38. How to Squeeze Test Driven Development on Legacy Systems We all love T.D.D. We know its benefits, we have read a thousand tutorials on how to build a system using this technique. But this not feasible for currently legacy systems. 39. Object-Oriented Design: Refactoring a REST Connector In this story we will try to see how to improve a simple REST connector that places a request on an external service through an HTTP POST call and returns the result back from the remote server.
The full example can be found here.
Following is the source code for our connector (Connector1): 40. Refactoring With Tests in Python: a Practical Example This post contains a step-by-step example of a refactoring session guided by tests. When dealing with untested or legacy code refactoring is dangerous and tests can help us do it the right way, minimizing the amount of bugs we introduce, and possibly completely avoiding them. Thank you for checking out the 40 most read stories about Tdd on HackerNoon. to find the most read stories about any technology. Visit the /Learn Repo

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