Examples Of

`HASH()`

Non-cryptographic hash

Result type

INTEGER, BIGINT

Syntax

HASH (value [USING <hash>])

<hash> ::= CRC32

Table 1. `HASH` Function Parameter
Parameter	Description
value	Expression of value of any type;non-string or non-binary types are converted to string
hash	Non-cryptographic hash algorithm to apply

HASH returns a hash value for the input argument.If the input argument is not a string or binary type, it is converted to string before hashing.

The optional USING clause specifies the non-cryptographic hash algorithm to apply.When the USING clause is absent, the legacy PJW algorithm is applied;this is identical to its behaviour in previous Firebird versions.

This function fully supports text BLOBs of any length and character set.

Supported algorithms

not specified: When no algorithm is specified, Firebird applies the 64-bit variant of the non-cryptographic PJW hash function (also known as ELF64).This is a fast algorithm for general purposes (hash tables, etc.), but its collision quality is suboptimal.Other hash functions — specified explicitly in the USING clause, or cryptographic hashes through [fblangref50-scalarfuncs-crypthash] — should be used for more reliable hashing.

The HASH function returns BIGINT for this algorithm
CRC32: With CRC32, Firebird applies the CRC32 algorithm using the polynomial 0x04C11DB7.

The HASH function returns INTEGER for this algorithm.

Examples Of

Examples of CRYPT_HASH

HASH()

Examples of `CRYPT_HASH`

`HASH()`