SQL, the language that reigns supreme in the world of relational databases, offers an array of features to manipulate and analyze data effectively. A notably powerful feature among them is the SQL window functions. Window functions enable computations across a… Read More »Comprehensive Guide to SQL Window Functions
Copying Only Data You can create a copy of an existing table in SQL by using the CREATE TABLE AS statement. This statement creates a new table and fills it with data computed by a SELECT command. The data types… Read More »How do you create a copy of an existing table in SQL?
Understanding Deadlocks in Databases In the context of databases, deadlocks are situations where two or more transactions are unable to proceed because each is waiting for the other to release a resource. This can be likened to a circular chain… Read More »Database Deadlocks: Reasons and Resolution
Cardinality, in the context of databases, is a critical concept that has two primary applications: it pertains to the uniqueness of data elements within a column, and it describes the nature of relationships between different tables.
Introduction The dynamics of database management prioritize efficient data retrieval as a key performance index. Herein lies the significance of database statistics, which provide a snapshot of database content like row counts in a table or value distributions within a… Read More »What is the Importance of Database Statistics in Query Optimization?
Introduction A phantom read is a scenario that occurs in a database when a transaction re-executes a query and finds that another committed transaction has added or removed rows that weren’t there previously. This anomaly can lead to inconsistencies in… Read More »What is a Phantom Read Anomaly?
Non-Repeatable Read is a database anomaly that occurs in the context of transactions, which are sequences of database operations that should behave as single, indivisible units of work. Non-Repeatable Read happens when a transaction reads the same row twice, and gets different data each time. This is usually due to another transaction modifying the data after the first read. In this post, we look at this concept in detail and techniques to address this.
What is a Dirty Read By definition, a dirty read occurs when a transaction reads data from another transaction that has not yet been committed. The “dirty” moniker refers to the potential unstable state of the data, as it is… Read More »How do ‘Dirty Reads’ Impact Database Consistency?
Database isolation is a property that defines how and when the changes made by one operation become visible to other concurrent operations. Isolation is one of the ACID (Atomicity, Consistency, Isolation, Durability) properties.
In this post, we will look at 4 standard isolation levels along with some database-specific ones.
ACID is a fundamental concept in database systems, standing for Atomicity, Consistency, Isolation, and Durability. These properties ensure reliable processing of database transactions. ACID Properties of Database Systems Atomicity Atomicity ensures that a transaction is treated as a single, indivisible… Read More »What is ACID in database systems?