Hash Functions

This page provides a comprehensive overview of Hash functions in Databend, organized by functionality for easy reference.

Cryptographic Hash Functions

Function	Description	Example
MD5	Calculates an MD5 128-bit checksum	MD5('1234567890') → 'e807f1fcf82d132f9bb018ca6738a19f'
SHA1 / SHA	Calculates an SHA-1 160-bit checksum	SHA1('1234567890') → '01b307acba4f54f55aafc33bb06bbbf6ca803e9a'
SHA2	Calculates SHA-2 family hash (SHA-224, SHA-256, SHA-384, SHA-512)	SHA2('1234567890', 256) → 'c775e7b757ede630cd0aa1113bd102661ab38829ca52a6422ab782862f268646'
BLAKE3	Calculates a BLAKE3 hash	BLAKE3('1234567890') → 'e2cf6ae2a7e65c7b9e089da1ad582100a0d732551a6a07abb07f7a4a119ecc51'

Non-Cryptographic Hash Functions

Function	Description	Example
XXHASH32	Calculates an xxHash32 32-bit hash value	XXHASH32('1234567890') → 3768853052
XXHASH64	Calculates an xxHash64 64-bit hash value	XXHASH64('1234567890') → 12237639266330420150
SIPHASH64 / SIPHASH	Calculates a SipHash-2-4 64-bit hash value	SIPHASH64('1234567890') → 2917646445633666330
CITY64WITHSEED	Calculates a CityHash64 hash with a seed value	CITY64WITHSEED('1234567890', 42) → 5210846883572933352

Usage Examples

Data Integrity Verification

-- Calculate MD5 hash for file content verification
SELECT 
  filename,
  MD5(file_content) AS content_hash
FROM files
ORDER BY filename;

Data Anonymization

-- Hash sensitive data before storing or processing
SELECT 
  user_id,
  SHA2(email, 256) AS hashed_email,
  SHA2(phone_number, 256) AS hashed_phone
FROM users;

Hash-Based Partitioning

-- Use hash functions for data distribution
SELECT 
  XXHASH64(customer_id) % 10 AS partition_id,
  COUNT(*) AS records_count
FROM orders
GROUP BY partition_id;