Hive simple instructions for use, hive simple instructions for use

Hive simple instructions for use, hive simple instructions for use

I usage:

Hive: Start hive

The command must end with a semicolon and tell hive to execute the command immediately, case insensitive.

Show tables; View tables

Desc tablename; view the columns in the table

Write SQL commands

Use udw;

Select user_id, action_id

From udw_ml_user_action

Where partition_date & gt; = 20150410

Distribute by user_id

Sort by user_id, action_id

Limit 10;

Execute SQL: hive-f test. SQL

Export Search Results: redirect to another format file: hive-f *. SQL> a.txt

II. data query commands

Order by: fully ordered, but only completed by a reducer. The efficiency of large-scale data sets is relatively low.

Sort by: generates a sorting file for each reducer.

Distribute by: determines the CER to which a specific row should be directed. For example, distribute by year ensures that all rows with the same year are eventually in the same CER partition.

Group by: group rows based on fields