Impala Tutorial
Database Specific Statements
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Impala - Clauses
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Database Specific Statements
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Impala - Clauses
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Impala - Limit Clause
Impala - Limit Clause
The pmit clause in Impala is used to restrict the number of rows of a resultset to a desired number, i.e., the resultset of the query does not hold the records beyond the specified pmit.
Syntax
Following is the syntax of the Limit clause in Impala.
select * from table_name order by id pmit numerical_expression;
Example
Assume we have a table named customers in the database my_db and its contents are as follows −
[quickstart.cloudera:21000] > select * from customers; Query: select * from customers +----+----------+-----+-----------+--------+ | id | name | age | address | salary | +----+----------+-----+-----------+--------+ | 3 | kaushik | 23 | Kota | 30000 | | 6 | Komal | 22 | MP | 32000 | | 1 | Ramesh | 32 | Ahmedabad | 20000 | | 5 | Hardik | 27 | Bhopal | 40000 | | 2 | Khilan | 25 | Delhi | 15000 | | 8 | ram | 22 | vizag | 31000 | | 9 | robert | 23 | banglore | 28000 | | 7 | ram | 25 | chennai | 23000 | | 4 | Chaitap | 25 | Mumbai | 35000 | +----+----------+-----+-----------+--------+ Fetched 9 row(s) in 0.51s
You can arrange the records in the table in the ascending order of their id’s using the order by clause as shown below.
[quickstart.cloudera:21000] > select * from customers order by id; Query: select * from customers order by id +----+----------+-----+-----------+--------+ | id | name | age | address | salary | +----+----------+-----+-----------+--------+ | 1 | Ramesh | 32 | Ahmedabad | 20000 | | 2 | Khilan | 25 | Delhi | 15000 | | 3 | kaushik | 23 | Kota | 30000 | | 4 | Chaitap | 25 | Mumbai | 35000 | | 5 | Hardik | 27 | Bhopal | 40000 | | 6 | Komal | 22 | MP | 32000 | | 7 | ram | 25 | chennai | 23000 | | 8 | ram | 22 | vizag | 31000 | | 9 | robert | 23 | banglore | 28000 | +----+----------+-----+-----------+--------+ Fetched 9 row(s) in 0.54s
Now, using the pmit clause, you can restrict the number of records of the output to 4, using the pmit clause as shown below.
[quickstart.cloudera:21000] > select * from customers order by id pmit 4;
On executing, the above query gives the following output.
Query: select * from customers order by id pmit 4 +----+----------+-----+-----------+--------+ | id | name | age | address | salary | +----+----------+-----+-----------+--------+ | 1 | Ramesh | 32 | Ahmedabad | 20000 | | 2 | Khilan | 25 | Delhi | 15000 | | 3 | kaushik | 23 | Kota | 30000 | | 4 | Chaitap | 25 | Mumbai | 35000 | +----+----------+-----+-----------+--------+ Fetched 4 row(s) in 0.64sAdvertisements