Programming/Algorithm Question:You are acting as a bank. You are given a list of customers’ transactions.The transactions can be either a deposit (positive value) or awithdrawal(negative value). The initial balance in…
Ace Your Data Engineering Interview: Essential LeetCode SQL, Python, and ETL Questions
CAP theorem Lambda vs kapp architecture Star vs snowflake schema Data warehouse , data lake, delta lake, dataware house Scd types SQL How would you write a query to calculate…
Surrogate keys are artificially generated primary keys, typically integers, used to uniquely identify records. In data warehouse you may have same record with multiple entries(this records columns value may change…
SQL also supports the use of aggregate expressions (or functions) that allow you to summarize information about a group of rows of data. SELECT AGG_FUNC(column_or_expression) AS aggregate_description, … FROM mytable…
A JOIN clause is used to query and access data from multiple tables by using logical relationships between them. Join syntax SELECT column, another_column, … FROM mytable INNER/LEFT/RIGHT/FULL JOIN another_table…
To delete duplicates from a table, you’ll need to identify the duplicate rows first and then delete them using SQL. The approach varies slightly depending on whether you’re working with…
Identify duplicates criteria The first step is to define your criteria for a duplicate row. Do you need a combination of two columns to be unique together, or are you…
SQL LIMIT and OFFSET LIMIT: Limits the number of rows returned by a query OFFSET: Specifies how many rows to skip before returning the results Here’s an example of using…
Pyspak complete tutorial from scratch Shuffle: when data persists and is shared with other executors.whenever shuffle happens job is get divided into stages Driver Executor in the following diagram, the…
Vishal Jadhav