casefold() — PostgreSQL string function

Summary

casefold is a PostgreSQL built-in function in the String Functions group. PostgreSQL’s system catalog (pg_proc) describes it as: “fold case”.

Signature

casefold(text) → text

Argument and return types are taken from the pg_proc catalog; internal type names are shown using their readable SQL spellings (for example int4 is shown as integer). (Derived from the catalog — see the linked reference for the canonical documentation.)

Classification

• Category: String Functions
• Kind: Function
• Volatility: IMMUTABLE — Marked IMMUTABLE — it always returns the same result for the same arguments and can be used in indexes and other contexts that require immutability.
• Returns: text

Example

Illustrative form (replace placeholder values with your own data):

SELECT casefold('abc');

The example above is illustrative and is meant to show calling syntax only; consult the linked PostgreSQL documentation for exact semantics, edge cases and accepted argument combinations.

Version applicability

Based on the catalog across releases, casefold first appears in PostgreSQL 18. It is present in: 18, 19.

Related & references

• PostgreSQL built-in function index
• More String Functions

Reference: PostgreSQL documentation — String Functions.