SHA224

Compute the SHA-224 hash of a string and return it as a 56-character lowercase hexadecimal string.

Category: miscReturns: STRINGDialect: PostgreSql

Syntax

SHA224(str)

Description

## Overview Computes the SHA-224 cryptographic hash of the UTF-8-encoded input string and returns the digest as a lowercase hexadecimal string. SHA-224 is a truncated variant of SHA-256 that produces a 224-bit (28-byte) digest. Use SHA-224 when you want a SHA-2 family hash shorter than SHA-256, typically for compact fingerprints in catalog or lineage contexts. For new designs, prefer SHA-256 unless you have a specific reason to keep the digest shorter. ## Algorithm and output - Returns a 56-character lowercase hexadecimal string (`[0-9a-f]`). - The digest is 224 bits (28 bytes) long. - Compare values hex-for-hex; direct equality with `=` is collation-safe because output is ASCII. - The function does not emit the raw binary; use a separate encoding if you need bytes. ## Behavior - Returns NULL if the input is NULL. - Deterministic: equal inputs produce equal outputs. - Side effect free. - Hashes the UTF-8 encoding of the input string; different encodings produce different digests. ## Compatibility - PG-compat alias for the standard SHA-224 primitive.

Parameters

Name	Type	Description
`str`		Specifies the input string to hash. The input is hashed as its UTF-8 byte representation.

Examples

-- Hash a literal
SELECT SHA224('hello');

-- Hash an empty string (canonical SHA-224 of empty input)
SELECT SHA224('');

-- Same input produces the same digest
SELECT SHA224('abc') = SHA224('abc') AS same_hash;  -- true

-- Build a fingerprint column for change detection
SELECT customer_id, SHA224(CONCAT_WS('|', first_name, last_name, email)) AS fp
FROM crm.catalog.customers;

-- NULL propagation
SELECT SHA224(NULL);  -- NULL

Pitfalls

SHA-224 is not appropriate for password storage; like all plain hashes, it is too fast for modern password attacks. Use a dedicated password KDF (Argon2, bcrypt, scrypt) for credentials.
The digest is hex-encoded. Do not compare digests after applying upper/lowercase or a different collation; compare the literal hex output.
NULL propagates. `SHA224(NULL)` is NULL, not the hash of 'NULL' or an empty string. Use `COALESCE(str, '')` upstream if you want a deterministic value for missing inputs.
The hash is over the UTF-8 encoding of the string. Hashing the same text under a different encoding produces a different digest; normalize the input upstream if you mix sources.