Linear hashing: Difference between revisions

Revision as of 06:14, 23 October 2023

Revision as of 23:44, 23 October 2023

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===Split control===

AAn '''uncontrolled split''' canoccurs bewhen a split is performed whenever a bucket overflows. This is an uncontrolled split.

Alternatively, the file can monitor the load factor and performs a split whenever

'''Controlled splitting''' occurs if a split is performed whenever the load factor, which is monitored by the file, exceeds a predetermined threshold.<ref name="LMS" /> If the hash index uses controlled splitting, the buckets are allowed to overflow by using linked overflow blocks. When the records/buckets ratio surpasses a set threshold, the designated bucket is split. This threshold can also be expressed as an occupancy percentage, in which case, the maximum number of records in the hash index equals (occupancy percentage)*(max records per non-overflowed bucket)*(number of buckets).<ref>{{Cite book |last=Silberschatz |first=Abraham |title=Database system concepts |last2=Korth |first2=Henry F. |last3=Sudarshan |first3=S. |date=2020 |publisher=McGraw-Hill Education |isbn=978-1-260-08450-4 |edition=Seventh edition |___location=New York, NY}}</ref>

the load factor exceeds a threshold. This was controlled splitting.<ref name=LMS/>

===Addressing===