36 results about "Perfect hash function" patented technology

Techniques for managing data objects of a data storage system are described herein. According to one embodiment, a perfect hash function is generated for data objects stored in a data storage system. For each of the data objects, a hash operation is performed using the perfect hash function to indicate whether the respective data object is alive. Resources associated with the respective data object is reclaimed if it is determined that the respective data object is not alive based on a result of the hash operation using the perfect hash function, where the reclaimed resources are released back to the data storage system as free resources. Other methods and apparatuses are also described.

A recursively partitioned static router-table, the data structure incorporating a first-level partition including subtries and an auxiliary trie. A node of the subtrie includes a path Q(N) from the root R of a trie T to a root N of the subtrie, a stride s for a next-level partition, a mask that characterizes a next-level perfect hash function, and a pointer to the hash table for the next-level partition. At least one of the trie T, the first-level partition, the auxiliary trie, and the next-level partition is represented by a base structure selected from the group consisting of MBT and HSST.

A high-speed, space-efficient, scalable and easily updateable data boundary hash-based structure is generated and used. The proposed boundary hash-based data structure provides minimal perfect hashing functionality while intrinsically supporting low-cost set-membership queries. In other words, in some embodiments, it provides at most one match candidate in a set of known arbitrary-length bit strings that is used to match the query.

Hardware circuitry may evaluate minimal perfect hash functions mapping keys to addresses in lookup tables. The circuitry may include primary hash function sub-circuits that apply linear hash functions to input key values (using carry-free arithmetic) to produce primary hash values. Each sub-circuit may multiply bit vectors representing key values by a bit matrix and add a constant bit vector to the result. The circuitry may include a secondary hash function sub-circuit that generates secondary hash values by aggregating values associated with multiple primary hash values using signed, unsigned, or modular integer addition, or bit-wise XOR operations. Secondary hash values may be usable to access data values in the lookup table that are associated with particular input key values. The circuitry may determine the validity of input keys and may alter the configuration or contents of the lookup tables. The hash function sub-circuits may include programmable hash tables.

A “Variable-Rate Perfect Hasher” maps sparse variable-rate data of one or more dimensions into a hash table using a perfect hash function. In various embodiments, perfect hash tables are populated by first computing offset table address for each data point of a domain of sparse variable-rate data elements. Offset vectors are then computed for each offset table address based in part on the size of each data element by evaluating offset vectors in order of a sum of the data point addresses mapping to each offset vector. These offset vectors are then stored in the offset table. For each data point, the corresponding offset vector is then used to compute a hash table address. Data elements are then perfectly hashed into the hash table using the computed hash table addresses. The resulting hash tables support efficient random access of the variable-sized data elements stored therein.

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.

Generating and using a high-speed, scalable, and easily updateable data structure are described. The proposed data structure provides minimal perfect hashing functionality while intrinsically supporting low-cost set-membership queries. In other words, in some embodiments, it provides at most one match candidate in a set of known arbitrary-length bit strings that is used to match the query.

Generating and using a high-speed, scalable and easily updateable data structures are described. The proposed data structure provides minimal perfect hashing functionality while intrinsically supporting low-cost set-membership queries. In other words, in some embodiments, it provides at most one match candidate in a set of known arbitrary-length bit strings that is used to match the query.

Embodiments are directed to perfect physical garbage collection (PPGC) process that uses a NUMA-aware perfect hash vector. The process splits a perfect hash vector (PHVEC) into a number of perfect hash vectors, wherein the number corresponds to a number of nodes having a processing core and associated local memory, directs each perfect hash to a respective local memory of a node so that each perfect hash vector accesses only a local memory, and assigns fingerprints in the perfect hash vector to a respective node using a mask function. The process also performs a simultaneous creation of perfect hash vectors in a multi-threaded manner by scanning the Index once.

A representation of a new rule, defined as a set of a new transition(s), is inserted into a perfect hash table which includes previously placed transitions to generate an updated perfect hash table. This may be done by, for each new transition: (a) hashing the new transition; and (b) if there is no conflict, inserting the hashed new transition into the table. If, however, the hashed new transition conflicts with any of the previously placed transitions, either (A) any transitions of the state associated with the conflicting transition are removed from the table, the hashed new transition is placed into the table, and the removed transitions are re-placed into the table, or (B) any previously placed transitions of the state associated with the new transition are removed, and the transitions of the state associated with the new transition are re-placed into the table.

A system and method that allows two parties to find common records in their data sets without having to actually share the data sets with each other or a third party. Two primitives, perfect hash functions and public key cryptography, are combined in a unique way to obtain a secure and efficient private matching solution. Since the data that is exchanged is always encrypted during the match process, neither party reveals its data to the other party. This solution enables two parties to match sensitive data such as PII (Personally Identifiable Information) or PHI (Protected Health Information) without having to disclose the data to other or to any third party. One or both of the parties only learn of matching records without learning any information about the records that do not match.

The embodiment of the application discloses a gateway message forwarding method, device, storage medium and gateway, which belong to the technical field of communication. The method includes: receiving a CAN message sent by a first node; obtaining identification information from the CAN message; performing a hash operation on the identification information using a minimum perfect hash function to obtain a minimum perfect hash value; according to The minimum perfect hash value is searched for a second node in a routing table; and the CAN message is forwarded to the second node. In the embodiment of the present application, the minimum perfect hash value is calculated for the identification information through the minimum perfect hash function. Since the minimum perfect hash values ​​calculated according to different identification information are different, there will be no hash collision. It can also ensure that the CAN messages of all nodes can be forwarded in real time, reducing the delay of message forwarding.