Hive Overview Notes

• Data Warehousing package built on top of hadoop
• Managing and querying structured data
• Apache Derby embedded DB used by Hive
• metastore_db folder for persistence of data
• Suitable for WORM - Write Once Read Many Times Access Pattern
• Core Components are Shell, Metastore, Execution Engine, Compiler (Parse, Plan, Optimize), Driver
• Tables can be created as Internal Tables, External Table (Pointing to external file)
• When Internal Tables are dropped schema + data is dropped. For external referencing tables only Schema is dropped not data. Both Internal and External tables reside in HDFS
• Data files for created tables would be available in location /user/hive/warehouse
• Partitioning in Hive - Hash Value % Number of buckets - that particular row will go into that bucket
• Partition table should always be an Internal Hive Table

Happy Learning!!!