Many of you may have heard or used MySQL's query cache, because it used to be a popular way to improve MySQL's performance. As an important feature for improving MySQL's performance, the query cache was often recommended as a solution for slow queries. However, why has MySQL 8 abandoned the query cache? Today, we will analyze and explore this decision.What is query cache?According to official document:The query cache stores the text of a SELECT statement together with the corresponding result that was sent to the client. If an identical statement is received later, the server retriev...

ClosureThe official definition of closure is: an expression (usually a function) that has many variables and is bound to an environment that includes those variables.In JavaScript, closure refers to the ability of a function to access the lexical scope in which it was defined, even after the function has been executed and left that scope. This ability is due to the fact that when a function is created, it generates a closure that includes a reference to the definition environment of the current function, allowing the function to continue to access those variables within that environment.Below ...

As a high-performance in-memory database, Redis is widely used in current mainstream distributed architecture systems. To improve system fault tolerance, using multiple instances of Redis is also inevitable, but the complexity is much higher than that of a single instance. This article mainly introduces the four deployment modes of Redis and their advantages and disadvantages.StandaloneStandalone mode is to install a Redis, start it, and business connects to it and that's all. The specific installation and startup steps are not repeated here. Standalone mode is also used in many scenarios, suc...

Redis is a high-performance, in-memory key-value database. According to official test reports, it can support around 100,000 QPS (queries per second) on a single machine. However, Redis uses a single-threaded architecture in its design.Why does Redis still have such high performance with a single-threaded design? Wouldn't it be better to use multiple threads for concurrent request processing?In this article, let's explore why Redis has a single-threaded architecture and still maintains its speed. The focus is on the following four aspects:Data storage in memoryEfficient data structuresSingle-t...

BackgroundThe Go 1.20 version was officially released in February 2023, it introduced the PGO(Profile Guided Optimization) mechanism.The basic principle of PGO can be divided into the following two steps:First, profiling is performed on the program to collect data about the program's runtime and generate a profiling file.When compiling the program, enable the PGO option, and the compiler will optimize the program's performance based on the content in the .pgo file.When compiling a program, the compiler will perform many optimizations, including well-known optimizations such as inline optimizat...

WordPress is a popular content management system (CMS) used by millions of websites around the world. According to data from W3Techs.com, at least 64.2% of websites that have CMS use WordPress’s system.However, to run a WordPress website, you need a hosting provider that can support it. There are many hosting providers that offer specialized WordPress hosting. For example, they would provide seamless, one-click WordPress migrations, or dedicate a team of experts to address any WordPress-related customer concerns.  The quality and reliability of WordPress hosting providers can v...

In JavaScript, deep clone means creating a brand new object that includes all nested objects, with all properties being completely independent copies. This is different from shallow copying, which only copies the first-level properties, with nested objects being referenced rather than copied.There are multiple ways to perform deep copying in JavaScript, but the best one to use depends on the specific use case.Can use JSON.parse & JSON.stringify? ❌JSON.parse(JSON.stringify(obj)) is a depth cloning method that uses JSON serialization to create an object. It works for objects that do not co...

Creating a web scraper is no easy task. This is because it requires precision to identify the specific data points that we intend to collect for the end goal we are working towards. Whether we are looking to create a marketing content database or analyze market trends, the last thing we need from our scraper is for it to return a lot of unnecessary data that will not help our cause.To avoid the inconvenience of going through huge amounts of data to get what we requested, it is crucial to plan beforehand and include a parser in our web scraper. This is where CSS selectors come in, as they ...