What is Hive?

• is an open-source data warehouse system
• built on top of Hadoop for querying and analyzing large datasets
• is a NOT relational database
• is NOT designed for online transaction progress
• Access to data via SQL-like queries (HiveQL)
• Data summarization and aggregation
• Analysis

Hive is an open-source data warehouse system built on top of Hadoop for querying and analyzing large datasets. Hive abstracts the complexity of Hadoop. It provides easy to use SQL-like syntax called HiveQL, and enables users to do ad-hoc querying, summarization and data analysis. Hive implicitly converts HiveQL statements into a directed acyclic graph (有向无环图) of MapReduce, Tez, or Spark jobs, which are submitted to Hadoop for execution.

Hive is more suitable for traditional data warehousing tasks.

1. Metastore could be configured as:

   • Embedded (derby DB)
   • Local
   • Remote
2. Metastore DB: RDBS - MySQL, Oralce, Postgres, MS-SQL.

Data Units

1. Partitions

2. Buckets

• Sampling 采样