Spring MVC is a module in the Spring framework that helps you build web applications. It is a framework that helps you build web applications in a clean and modular way, by providing a structure for request handling and a model-view-controller design pattern.

Spring makes programming Java quicker, easier, and safer. Spring’s focus on speed, simplicity, and productivity has made it the world’s most popular Java framework. Spring works on microservices, reactive, cloud, web apps, serverless, event driven, and batch services.

Spark SQL is the top active component in spark 3.0 release. Most of the resolved tickets are for Spark SQL. These enhancements benefit all the higher-level libraries, including structured streaming and MLlib, and higher level APIs, including SQL and DataFrames. Various related optimizations are added in latest release.

There is a problem about word segmentation when I use Chinese in ES. Elasticsearch is the distributed, restful search and analytics engine. You can use Elasticsearch to store, search, and manage data for Logs，Metrics，A search backend，Application monitoring，Endpoint security.

CAPTCHA stands for ‘Completely Automated Public Turing test to tell Computers and Humans Apart’. It’s already possible to solve it with the rise of deep learning and computer vision.

Flink optimization includes resource configuration optimization, back pressure processing, data skew, KafkaSource optimization and FlinkSQL optimization.

There are systems that can store values of different columns separately, but that can’t effectively process analytical queries due to their optimization for other scenarios. Examples are HBase and BigTable. You would get throughput around a hundred thousand rows per second in these systems, but not hundreds of millions of rows per second.

Data warehouse is a system that pulls together data derived from operational systems and external data sources within an organization for reporting and analysis. A data warehouse is a central repository of information that provides users with current and historical decision support information.