Tag: sql
9 articles
Hive Slowly Changing Dimension Type 2: Order History Stat...
Offline data warehouse needs to save order history state at low cost while supporting daily rollback and change analysis. This article introduces using ODS...
MySQL ShardingSphere: SQL Parse, Route, Rewrite & Execute...
Deep dive into ShardingSphere's sharding flow including SQL parsing, query optimization, SQL routing, SQL rewriting, SQL execution and result merging six major stages with detailed technical analysis.
SparkSQL Statements: DataFrame Operations, SQL Queries & ...
Comprehensive guide to SparkSQL core usage including DataFrame API operations, SQL query syntax, lateral view explode, and Hive integration via enableHiveSupport for metadata and table operations.
SparkSQL Kernel: Five Join Strategies & Catalyst Optimize...
Deep dive into SparkSQL's five Join execution strategies (BHJ, SHJ, SMJ, Cartesian, BNLJ) selection conditions and use cases, along with the complete processing flow of Catalyst optimizer from SQL ...
SparkSQL Core Abstractions: RDD, DataFrame, Dataset & Spa...
Deep comparison of Spark's three data abstractions RDD, DataFrame, Dataset features and use cases, introduction to SparkSession unified entry, and demonstration of mutual conversion methods between...
SparkSQL Operators: Transformation & Action Operations
Systematically review SparkSQL Transformation and Action operators, covering select, filter, join, groupBy, union operations, with practical test cases demonstrating usage and performance optimizat...
SparkSQL Introduction: SQL & Distributed Computing Fusion
Systematic introduction to SparkSQL evolution history, core abstractions DataFrame/Dataset, Catalyst optimizer principle, and practical usage of multi-data source integration with Hive/HDFS.
Hive DDL and DML Operations
Systematic explanation of Hive DDL (database/table creation, internal and external tables) and DML (data loading, insertion, query) operations, with complete HiveQL examples and configuration optim...
Hive HQL Advanced: Data Import/Export and Query Practice
Deep dive into Hive's multiple data import methods (LOAD/INSERT/External Table/Sqoop), data export methods, and practical usage of HQL query operations like aggregation, filtering, and sorting.