Author: lochan2014
Q1.–We are working with large datasets in PySpark, such as joining a 30GB table with a 1TB table or Various Transformation on 30 GB Data, we have 100 cores limit to use per user , what can be best configuration and Optimization strategy to use in pyspark ? will 100 cores are enough or should…
Spark Configuration, Monitoring, and Tuning, covering theory + code examples Here’s a comprehensive guide to Spark Configuration, Monitoring, and Tuning, covering theory + code examples. It’s especially helpful for Data Engineers working on performance optimization or preparing for interviews. ⚙️ Spark Configuration, Monitoring, and Tuning 🔧 1. Understand Components of the Spark Cluster A Spark…
Data cleaning in SQL is a crucial step in data preprocessing, especially when working with real-world messy datasets. Below is a structured breakdown of SQL data cleaning steps, methods, functions, and complex use cases you can apply in real projects or interviews. ✅ Common SQL Data Cleaning Steps & Methods Step Method / Function Example…
Question:-“What really happens inside the Spark engine when I run a simple .read() or .join() on a file?” Let me break this down in a clear, interview-ready, cluster-level Spark execution flow, step-by-step: 🔍 Spark Cluster Background Process (Example: spark.read.csv(…)) Imagine this code: Let’s analyze it in chronological order: ✅ 1. Driver Program Starts the Spark…
This is a fantastic deep-dive! Let’s answer your question clearly and technically: ✅ Question Recap: If I read a 1 GB CSV file or a 1 GB Hive table into a DataFrame —❓ Does defaultParallelism apply?❓ How are tasks created and executed in this case? 🔧 Short Answer: No, defaultParallelism does not directly control how…
Advanced-level PySpark, Big Data systems, and backend engineering—here’s a breakdown of what questions you can expect, based on industry trends. ✅ Topic-wise Breakdown of Likely Questions 🔹 PySpark & Big Data (Core Focus) Area Sample Questions PySpark DataFrame APIs – How is selectExpr different from select?- Use withColumn, explode, filter in one chain.- Convert nested…
Hive a Data warehouse infra Hive is an open-source data warehouse infrastructure built on top of Hadoop for providing data summarization, query, and analysis. It allows users to query and manage large datasets residing in distributed storage using a SQL-like language called HiveQL. Here’s an overview of Hive: Features of Hive: Components of Hive: Use…
Understanding how an SQL query executes in a database is essential for performance tuning and system design. Here’s a step-by-step breakdown of what happens under the hood when you run an SQL query like: 🧭 0. Query Input (Your SQL) You submit the SQL query via: ⚙️ Step-by-Step SQL Query Execution 🧩 Step 1: Parsing…
Here’s a comprehensive guide to important and tricky conceptual issues in SQL, including NULL behavior, joins, filters, grouping, ordering, and subqueries. ✅ 1. NULLs: The #1 source of confusion a. NULL ≠ NULL b. NOT IN with NULL c. Arithmetic with NULL ✅ 2. JOIN Issues a. INNER JOIN drops unmatched rows. b. LEFT JOIN…
Where to Use Python Traditional Coding in PySpark Scripts Using traditional Python coding in a PySpark script is common and beneficial for handling tasks that are not inherently distributed or do not involve large-scale data processing. Integrating Python with a PySpark script in a modular way ensures that different responsibilities are clearly separated and the…