In Snowflake, the LIMIT and FETCH clauses are used to limit the number of rows returned by a query. While they both serve a similar purpose, they have some important differences in terms of syntax and behavior. In this article, we will explore these differences and provide examples of how to use each clause effectively.
The LIMIT Clause
The LIMIT clause is used to specify the maximum number of rows that should be returned by a query. The syntax for the LIMIT clause is as follows:
SELECT column1, column2, ...
FROM table_name
LIMIT row_count;
Here, row_count is the maximum number of rows that should be returned by the query. For example, if we want to return only the first 10 rows of a table named freshers_in.customers, we can use the following query:
SELECT *
FROM freshers_in.customers
LIMIT 10;
This query will return the first 10 rows of the customers table.
It’s important to note that the LIMIT clause does not guarantee that exactly row_count rows will be returned by the query. If the table has fewer rows than the specified limit, only the available rows will be returned.
The FETCH Clause
The FETCH clause is used to specify a subset of rows that should be returned by a query. The syntax for the FETCH clause is as follows:
SELECT column1, column2, ...
FROM table_name
FETCH FIRST row_count ROWS ONLY;
Here, row_count is the number of rows that should be returned by the query. For example, if we want to return the first 10 rows of a table named freshers_in.customers, we can use the following query:
SELECT *
FROM freshers_in.customers
FETCH FIRST 10 ROWS ONLY;
This query will return the first 10 rows of the customers table.
Unlike the LIMIT clause, the FETCH clause guarantees that exactly row_count rows will be returned by the query. If the table has fewer rows than the specified fetch count, the query will return an empty result set.
Differences between LIMIT and FETCH
The main difference between the LIMIT and FETCH clauses is in their behavior when there are fewer rows in the table than the specified limit or fetch count. While the LIMIT clause will return all available rows up to the specified limit, the FETCH clause will return an empty result set.
Another difference is in their syntax. The LIMIT clause simply specifies the maximum number of rows that should be returned, while the FETCH clause requires the use of the FIRST keyword and the explicit specification of the number of rows to be returned.
Suggested usage
In general, it’s recommended to use the FETCH clause when you need to retrieve a specific number of rows from a table. This is because the FETCH clause guarantees that exactly the specified number of rows will be returned, which can be important for applications that require consistency in their results.
On the other hand, the LIMIT clause can be useful for cases where you want to limit the amount of data returned by a query for performance reasons. For example, if you have a large table and you only need to see a small sample of the data, using the LIMIT clause can help to reduce the amount of data that needs to be processed and returned by the query.
The LIMIT and FETCH clauses are both useful tools for limiting the number of rows returned by a query in Snowflake. While they serve similar purposes, they have important differences in syntax and behavior. By understanding these differences and using each clause appropriately, you can write more efficient and effective queries in Snowflake.
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