The problem with most hashing functions is that they do not guarantee a unique address, because the number of possible values a hash field can take is typically much larger than the number of available addresses for records. Each address generated by a hashing function corresponds to a page, or bucket, with slots for multiple records. Within a bucket, records are placed in order of arrival. When the same address is generated for two or more records, a collision is said to have occurred (the records are called synonyms). In this situation, we must insert the new record in another position, because its hash address is occupied. Collision management complicates hash file management and degrades overall performance. There are several techniques that can be used to manage collisions:
The problem with most hashing functions is that they do not guarantee a unique address, because the number of possible values a hash field can take is typically much larger than the number of available addresses for records. Each address generated by a hashing function corresponds to a page, or bucket, with slots for multiple records. Within a bucket, records are placed in order of arrival. When the same address is generated for two or more records, a collision is said to have occurred (the records are called synonyms). In this situation, we must insert the new record in another position, because its hash address is occupied. Collision management complicates hash file management and degrades overall performance. There are several techniques that can be used to manage collisions:
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