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Oracle® Database SQL Language Reference
11g Release 1 (11.1)

B28286-07
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ORA_HASH

Syntax

Description of ora_hash.gif follows
Description of the illustration ora_hash.gif

Purpose

ORA_HASH is a function that computes a hash value for a given expression. This function is useful for operations such as analyzing a subset of data and generating a random sample.

The function returns a NUMBER value.

Examples

The following example creates a hash value for each combination of customer ID and product ID in the sh.sales table, divides the hash values into a maximum of 100 buckets, and returns the sum of the amount_sold values in the first bucket (bucket 0). The third argument (5) provides a seed value for the hash function. You can obtain different hash results for the same query by changing the seed value.

SELECT SUM(amount_sold) FROM sales
   WHERE ORA_HASH(CONCAT(cust_id, prod_id), 99, 5) = 0;

SUM(AMOUNT_SOLD)
----------------
       989431.14