STANDARD_HASH

Syntax

Description of the illustration standard_hash.gif

Description of the illustration standard_hash.eps

Purpose

STANDARD_HASH computes a hash value for a given expression using one of several hash algorithms that are defined and standardized by the National Institute of Standards and Technology. This function is useful for performing authentication and maintaining data integrity in security applications such as digital signatures, checksums, and fingerprinting.

You can use the STANDARD_HASH function to create an index on an extended data type column. Refer to “Creating an Index on an Extended Data Type Column” for more information.

• The expr argument determines the data for which you want Oracle Database to compute a hash value. There are no restrictions on the length of data represented by expr, which commonly resolves to a column name. The expr cannot be a LONG or LOB type. It cannot be a user-defined object type. All other data types are supported for expr.

• The optional method argument lets you specify the name of the hash algorithm to be used. Valid algorithms are SHA1, SHA256, SHA384, SHA512, and MD5. If you omit this argument, then SHA1 is used.

The function returns a RAW value.

Note: The STANDARD_HASH function is not identical to the one used internally by Oracle Database for hash partitioning.