Most beginners fail interviews not because they don't know advanced concepts like Apache Kafka or ETL processing tools, but because they can't explain why a JOIN suddenly tripled their table's row count. SQL and Python are core for data engineering and can get you through roughly 60% of entry-level Data Engineering interviews. I once came across a resume which had around 25 tools (Hadoop, Flume, Sqoop, Kafka, Kubernetes, Spark, Cassandra) but when I questioned the difference

Caching is one of the most common techniques used to make applications faster. Instead of fetching the same data from a database or API every time a user requests it, an application can temporarily store that data in a cache. The next request can then be served much faster. But this raises an important question: If the original data changes, how does the cache know that its copy is no longer correct? The short answer is: a cache usually does not magically know. The applicatio