Spark Architecture
Darshini
Apache Spark is a distributed data processing framework designed for speed and scalability. It works internally through a combination of cluster computing, in-memory processing, and DAG execution. Below is a…
Darshini
Date functions
SQL provides various date functions to manipulate and extract information from date and time values. These functions vary slightly across different databases (MySQL, PostgreSQL, SQL Server, Oracle), but the core…
Accumulator
Accumulator in PySpark An accumulator in PySpark is a shared, mutable variable used for aggregating information across tasks. It allows workers to increment or add values to a shared variable…
Broadcast Variable
A broadcast variable in PySpark is a mechanism for efficiently sharing read-only data across all nodes in a cluster. It is especially useful when you have data that needs to…
Aggregations
Aggregations in PySpark involve performing summary computations on data, such as calculating sums, averages, counts, or other statistical measures. These operations are often used to gain insights from datasets, such…
Handling NULL in join condition
In SQL, the behavior of joins involving NULL values in the join conditions depends on the type of join used. Here’s a breakdown: 1. INNER JOIN Behavior: Rows with NULL…
REVOKE
The SQL REVOKE command is used to remove or withdraw permissions from users or roles, which were previously granted using the GRANT command. It is an essential tool for managing…
GRANT
The GRANT command in SQL is used to assign permissions to users or roles, enabling them to perform specific operations on database objects. These permissions are essential for managing access…
SELECT
The SQL SELECT command is one of the most fundamental and frequently used operations in relational database management. It retrieves data from one or more tables, enabling you to query…
UPDATE
The SQL UPDATE command is used to modify existing records in a table. It allows developers and database administrators to make changes to one or multiple rows based on specified…