Summary: Postgres integer types SMALLINT (2 bytes), INTEGER (4 bytes), and BIGINT (8 bytes) store whole numbers without a fractional component and do not support unsigned values. Use SMALLINT for small-range columns, INTEGER for general-purpose identifiers and counters, and BIGINT when values exceed the INTEGER limit of roughly 2.1 billion. Topics include integer arithmetic truncation and the auto-incrementing SERIAL, SMALLSERIAL, and BIGSERIAL pseudo-types for primary keys.

Work with integers in Postgres

In Postgres, integer data types are used for storing numerical values without a fractional component. They are useful as identifiers, counters, and many other common data modeling tasks. Postgres offers multiple integer types, catering to different ranges of values and storage sizes.

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Postgres supports three primary integer types. Choosing the appropriate integer type depends on the range of data expected.

1. SMALLINT: A small-range integer, occupying 2 bytes of storage. It's useful for columns with a small range of values.
2. INTEGER: The standard integer type, using 4 bytes of storage. It's the most commonly used since it balances storage/performance efficiency and range capacity.
3. BIGINT: A large-range integer, taking up 8 bytes. It's used when the range of INTEGER is insufficient.

Note that Postgres doesn't support unsigned integers. All integer types can store both positive and negative values.

Consider a database for a small online bookstore. Here, SMALLINT could be used for storing the number of copies of a book in stock, while INTEGER would be appropriate for a unique identifier for each book.

The query below creates a books table with these columns:

CREATE TABLE books (
    book_id INTEGER PRIMARY KEY,
    title TEXT NOT NULL,
    copies_in_stock SMALLINT
);

INSERT INTO books (book_id, title, copies_in_stock)
VALUES
    (1, 'War and Peach', 50),
    (2, 'The Great Gatsby', 20),
    (3, 'The Catcher in the Rye', 100);

Postgres supports various arithmetic operations on integer types, including addition, subtraction, multiplication, and division.

Note that the division of integers does not yield a fractional result; it truncates the result to an integer.

SELECT 10 / 4; -- Yields 2, not 2.5

Postgres also provides SERIAL, which is a pseudo-type for creating auto-incrementing integers, often used for primary keys. It's effectively an INTEGER that automatically increments with each new row insertion.

There is also BIGSERIAL and SMALLSERIAL for auto-incrementing BIGINT and SMALLINT columns, respectively.

For example, we can create an orders table with an auto-incrementing order_id column:

CREATE TABLE orders (
    order_id SERIAL PRIMARY KEY,
    order_details TEXT
);

INSERT INTO orders (order_details)
VALUES ('Order 1'), ('Order 2'), ('Order 3');
RETURNING *;

This query returns the following:

 order_id | order_details
----------+---------------
        1 | Order 1
        2 | Order 2
        3 | Order 3

The order_id column gets a unique integer value for each new order.

• Data integrity: Integer types strictly store numerical values. Attempting to insert non-numeric data, or a value outside the range of that particular type will result in an error.
• Performance: Choosing the correct integer type (SMALLINT, INTEGER, BIGINT) based on the expected value range can optimize storage efficiency and performance.

• PostgreSQL documentation - Numeric Types

• Array
• Boolean
• Date and time
• Character
• JSON
• Decimal
• Floating point
• Tsvector
• UUID

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