The library cache object hashing situation is more complicated than with block hashing. We're not dealing with a file number and a block number. This situation requires hashing the object's text. So if a SQL statement or a package is 2,000 lines long, Oracle may choose to hash all this text.

Generating a hash value for text is far more interesting than generating one for a number. One way to hash text is to associate each character with a number and then sum all the numbers. For example, if a is to 1, b is to 2, and c is to 3, then the hash value of string abbc is 8 (1 + 2 + 2 + 3). Figure 7-8 is a simple hash value generator and hash function Perl script.

Figure 7-8. Shown is an example of a text hashing and bucket assignment function written in Perl. The hash function is the modulus (%) operator.