impala truncated the table

Impala's True Table statement is used to delete all records from an existing table.

You can also use the DROP TABLE command to delete a complete table, but it removes the full table structure from the database, and if you want to store some data, you will need to re-create the table.

Grammar

The following is the syntax of the truncate table statement.

truncate table_name;

Cases

Suppose we have a table called customers in Impala, and if you verify its contents, you get the following results. T his means that the customers table contains six records.

[quickstart.cloudera:21000] > select * from customers; 

Query: select * from customers 
+----+----------+-----+-----------+--------+--------+ 
| id | name     | age | address   | salary | e_mail | 
+----+----------+-----+-----------+--------+--------+
| 1  | Ramesh   | 32  | Ahmedabad | 20000  | NULL   | 
| 2  | Khilan   | 25  | Delhi     | 15000  | NULL   | 
| 3  | kaushik  | 23  | Kota      | 30000  | NULL   |
| 4  | Chaitali | 25  | Mumbai    | 35000  | NULL   | 
| 5  | Hardik   | 27  | Bhopal    | 40000  | NULL   | 
| 6  | Komal    | 22  | MP        | 32000  | NULL   | 
+----+----------+-----+-----------+--------+--------+

The following is an example of truncate statements to truncate tables in Impala. H ere we delete all records of the table named Customers.

[quickstart.cloudera:21000] > truncate customers;

When executing the above statement, Impala deletes all records for the specified table and displays the following message.

Query: truncate customers 

Fetched 0 row(s) in 0.37s

Verify

If you verify the contents of the customers table, after deleting the operation, you will get an empty row using the select statement, as shown below.

[quickstart.cloudera:21000] > select * from customers;
Query: select * from customers 

Fetched 0 row(s) in 0.12s

Use The Hue browser to truncated the table

Open the Impala query editor and type the truncate statement in it. T hen click the execute button, as shown in the screenshot below.

After the query/statement is executed, all records in the table are deleted.