PostgreSQL - Size of value

The size of a value in a database table refers to the space required to store that specific value. Accurately gauging the storage requirements for different data types can be crucial for database optimization and performance. In this article, we will explore the 'pg_column_size()' function in PostgreSQL, which is used to determine the size of a value.

What is pg_column_size()?

The 'pg_column_size()' function in PostgreSQL is a built-in function that returns the number of bytes required to store a given value. This function is particularly useful for understanding the storage requirements of different data types and for optimizing the space usage in your database.

Syntax

SELECT pg_column_size(value::type);

Parameters

• value: The value for which you want to determine the storage size.
• type: The data type of the value.

PostgreSQL pg_column_size() Examples

Let us take a look at some of the examples to better understand the concept. Here we will be using a sample database for reference which is described here and can be downloaded from here.

Example 1: Space Required to Store Smallint Values

Here, we query the space required to store a value of the 'smallint' type.

SELECT pg_column_size(10::smallint);

Output:

Explanation: The output will show the number of bytes required to store the value '10' as a 'smallint'.

Example 2: Space Required to Store Int Values

This example demonstrates the space required to store a value of the 'int' type.

SELECT pg_column_size(10::int);

Output:

Explanation: The output will indicate the number of bytes required to store the value '10' as an 'int'.

Example 3: Space Required to Store Bigint Values

Here, we determine the storage space needed for a 'bigint' value.

SELECT pg_column_size(10::bigint);

Output:

Explanation: The output will display the number of bytes required to store the value '10' as a 'bigint'.

Conclusion

The 'pg_column_size()' function is a powerful tool for database administrators and developers to understand the storage requirements of different values in PostgreSQL. By using this function effectively, you can optimize your database's storage, improve performance, and ensure efficient use of space. Whether you are dealing with small integers or large text values, 'pg_column_size()' provides valuable insights into the space requirements of your data.