Introduction to EXPLAIN Plains An EXPLAIN plan, often simply called an “explain”, is a tool in SQL-based database systems like PostgreSQL that provides information about how a database will execute a given query. By inputting a SQL query to the… Read More »What is an EXPLAIN Plan? How is it interpreted?
A SQL Injection is a code injection technique that attackers use to exploit vulnerabilities in a web application’s database layer. This vulnerability is often present in a web application when user input is incorrectly filtered for string literals that are used in SQL statements, or when user input is not strongly typed and can unexpectedly execute SQL commands.
The technique allows an attacker to manipulate SQL queries that an application makes to its database, enabling the attacker to view, alter, or delete data that they are not normally authorized to access.
Introduction A distributed key-value store is a simple and effective database design. As the name implies, it allows storage of data in a key-value pair, allowing quick and efficient access to the data. Distributed means that the data is spread… Read More »How would you design a distributed key-value store?
Requirements Database Schema The core table you would need is a table to store the URL mappings: This schema is simplified for the demonstration. For a production system, additional data such as URL access statistics and user roles might be… Read More »Design a URL shortening system like bit.ly
Definition of Configuration Drift Configuration drift is a phenomenon occurring when production environments gradually diverge or “drift” from their initial, defined configurations. It can be caused by updates, patches, or adjustments made directly to servers, network devices, or other infrastructural… Read More »What is “Configuration Drift”?
Processing of Normal Non-Prepared Statements Non-prepared statements, also known as direct SQL statements, involve SQL queries being written and sent to the database directly. The steps involved in processing a normal SQL statement are: This whole process is repeated each… Read More »How Does a Database Engine Process Prepared Statements Compared to Normal Statements, and Why Are Prepared Statements Faster
Common Table Expressions (CTEs) provide a way to write auxiliary statements for use in a larger query. These auxiliary statements, essentially named subqueries, can be referenced later in the FROM clause. They make queries easier to understand by breaking them up into smaller, simpler parts.
A database cursor is a mechanism used to traverse through a set of data retrieved from a database. Cursors are commonly used in programming languages to execute queries that retrieve a large number of rows. Cursors allow for more control over the processing of data and can be used to perform tasks such as updating or deleting records. However, cursors can be resource-intensive and slow down performance, so they should only be used when necessary.
A view is a virtual table that is based on one or more tables, while a materialized view is a physical copy of a view that is stored on disk. Unlike views, materialized views can be indexed for faster access and can improve query performance in data-intensive environments.
In SQL (Structured Query Language), a JOIN operation combines rows from two or more tables based on a related column between them. A self-JOIN is a type of JOIN where a table is joined with itself. Essentially, it’s when you… Read More »Can you explain the concept of a self-JOIN and provide an example where it might be useful?