Exploring PostgreSQL 9.3’s Support for Whitespace in Column Names

PostgreSQL, as a robust and versatile database management system, allows column names to include whitespace and special characters. This flexibility is achieved through the use of quoted identifiers. This article will delve into the reasons, use cases, and best practices associated with allowing whitespace in PostgreSQL column names.

Quoted Identifiers: The Flexibility You Need

In PostgreSQL, when double quotes (") are used around an identifier, it allows the use of spaces, special characters, and even case sensitivity. This behavior is aligned with the SQL standard, which permits more flexible naming conventions through quoted identifiers. Let's take a look at an illustrative example:

Example Using Quoted Identifiers

CREATE TABLE "my_table" (
    "first_name" VARCHAR(50),
    "last_name" VARCHAR(50)
);

Note that column names such as "first_name" and "last_name" can now include spaces without causing any syntax errors.

Unquoted Identifiers: The Default Behavior

When identifiers are not enclosed in double quotes, PostgreSQL converts them to lowercase and does not allow spaces or special characters, except for underscores. Here’s an example:

Example Using Unquoted Identifiers

CREATE TABLE my_table (
    first_name VARCHAR(50),
    last_name VARCHAR(50)
);

In this example, first_name and last_name are converted to lowercase, and only _ is allowed as a special character.

Use Cases: Why Allow Whitespace?

Allowing whitespace in quoted column names can provide several benefits, including:

Compatibility with Legacy Systems: Legacy systems may have existing naming conventions that include whitespace. Supporting these conventions ensures seamless integration. Readable Names: Column names with spaces can be more descriptive and self-explanatory, making queries easier to understand and maintain.

For instance, consider creating a table named "Order Details" to store information about various orders:

CREATE TABLE "Order Details" (
    order_id INT,
    product_name VARCHAR(100)
);

The table name and column names are now more readable and aligned with common business practices.

Best Practices: When to Avoid Whitespace

While PostgreSQL support for quoted identifiers allows for flexibility, it is generally recommended to avoid using spaces in column names for the following reasons:

Better Readability: Column names using underscores (e.g., first_name) or camel case (e.g., firstName) are more readable and align with modern coding standards. Avoiding Confusion: Spaces in column names can sometimes cause confusion, especially in complex queries, reducing the chance of errors.

For example, consider the following table:

CREATE TABLE "Order Details" (
    order_id INT,
    product_name VARCHAR(100)
);

The column name product_name with a space can cause confusion, especially in large queries:

SELECT * FROM "Order Details" WHERE "product_name"  'Red apples';

In this example, the column name is cumbersome and less readable.

Conclusion: A Balance Between Flexibility and Readability

In summary, PostgreSQL 9.3 allows whitespace in column names through the use of double quotes. This feature aligns with the SQL standard and provides flexibility for naming conventions. However, it is recommended to use underscores or camel case for column names to maintain readability and prevent potential confusion in queries.

To check official documentation, the SQL-92 standard defines identifiers and their treatments in detail. Understanding and implementing these naming conventions can greatly enhance the manageability and maintainability of your PostgreSQL database.

Further Reading: For more detailed information, refer to the PostgreSQL Documentation.