What is the tool of hive
Editor to share with you what hive is a tool, I believe that most people do not know much about it, so share this article for your reference, I hope you will learn a lot after reading this article, let's go to understand it!
Hive is a data warehouse tool based on Hadoop, which can map structured data files to a database table, provide simple sql query function, and convert sql statements into MapReduce tasks to run. Its advantage is low learning cost, simple MapReduce statistics can be quickly realized through SQL-like statements, and there is no need to develop special MapReduce applications, so it is very suitable for statistical analysis of data warehouse.
Hive is a data warehouse infrastructure based on Hadoop, which provides a series of tools for data extraction, transformation and loading (ETL), which is a mechanism that can store, query and analyze large-scale data stored in Hadoop.
Hive defines a simple SQL-like query language called HQL, which allows users who are familiar with SQL to query data. At the same time, the language also allows familiar with MapReduce developers to develop custom mapper and reduce to handle complex analytical work that cannot be done by built-in mapper and reduce.
Hive has no special data format, hive can work well on Thrift, control delimiters, and allow users to specify data formats.
Hive is a sql parsing engine based on hadoop.
What you run in hive is that sql in sql.hive is very close to mysql's sql syntax.
Comparison of database, table, field, type in hiveQL with file structure on hadoop.
Database-folder
Table-folder
Data in table-data file in folder
Fields-columns in the data file
HiveQL run-MapReduce
The table information in hiveQL must be mapped to file information in HDFS, similar to Hibernate's configuration file (* .hmb.xml).
The mapping information is not stored in the file, but in RDBMS (derby,mysql).
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