Hive 基础介绍

1. Architecture of Hive

2.how hive works

Step No. Operation
1
Execute Query
The Hive interface such as Command Line or Web UI sends query to Driver (any database driver such as JDBC, ODBC, etc.) to execute.
2
Get Plan
The driver takes the help of query compiler that parses the query to check the syntax and query plan or the requirement of query.
3
Get Metadata
The compiler sends metadata request to Metastore (any database).
4
Send Metadata
Metastore sends metadata as a response to the compiler.

5
Send Plan
The compiler checks the requirement and resends the plan to the driver. Up to here, the parsing and compiling of a query is complete.
6
Execute Plan
The driver sends the execute plan to the execution engine.
7
Execute Job
Internally, the process of execution job is a MapReduce job. The execution engine sends the job to JobTracker, which is in Name node and it assigns this job to TaskTracker, which is in Data node. Here, the query executes MapReduce job.
7.1
Metadata Ops
Meanwhile in execution, the execution engine can execute metadata operations with Metastore.
8
Fetch Result
The execution engine receives the results from Data nodes.

9
Send Results
The execution engine sends those resultant values to the driver.
10
Send Results
The driver sends the results to Hive Interfaces.