Invention Grant
- Patent Title: Memory efficient perfect hashing for large records
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Application No.: US16159331Application Date: 2018-10-12
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Publication No.: US11010257B2Publication Date: 2021-05-18
- Inventor: Tony Wong , Hemanth Satyanarayana , Abhinav Duggal , Ranganathan Dhathri Purohith
- Applicant: EMC IP Holding Company LLC
- Applicant Address: US MA Hopkinton
- Assignee: EMC IP Holding Company LLC
- Current Assignee: EMC IP Holding Company LLC
- Current Assignee Address: US MA Hopkinton
- Agency: Staniford Tomita LLP
- Main IPC: G06F7/00
- IPC: G06F7/00 ; G06F17/00 ; G06F11/14 ; G06F16/13 ; G06F16/174 ; G06F16/901

Abstract:
Embodiments for a memory efficient perfect hashing for large records. A container ID set is divided into multiple fixed range sizes. These ranges are then mapped into perfect hash buckets until each bucket is filled to uniformly distribute the container IDs across different perfect hash buckets so that the number of CIDs in every perfect hash bucket is the same or nearly the same. Individual perfect hash functions are created for each perfect hash bucket. With container IDs as keys, the process maps n keys to n positions to reduce any extra memory overhead. The perfect hash function is implemented using a compress, hash, displace (CHD) algorithm using two levels of hash functions. The level 1 hash functions divides the keys into multiple internal buckets with a defined average number of keys per bucket. The CHD algorithm iteratively tries different level 2 hash variables to achieve collision-free mapping.
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