Abstract: Systems and techniques for reducing probabilistic filter query latency are described herein. A query for a probabilistic filter that is stored on a first media may be received from a caller. In response to receiving the query, cached segments of the probabilistic filter stored on a second media may be obtained. Here, the probabilistic filter provides a set membership determination that is conclusive in a determination that an element is not in a set. The query may be executed on the cached segments resulting in a partial query result. Retrieval of remaining data of the probabilistic filter from the first media to the second media may be initiated without intervention from the caller. Here, the remaining data corresponds to the query and data that is not in the cached segment. The partial query results may then be returned to the caller.

Abstract: A KVS tree database and operations thereon are described herein. A KVS tree database is a multilevel tree that includes a base level and subsequent levels. The base level includes a heterogeneous kvset in a node, The heterogeneous kvset including entries for multiple KVS trees, such as a first entry for a first KVS tree and a second entry for a second KVS tree, The subsequent level includes a first node including a first homogeneous kvset for the first KVS tree and a second node including a second homogeneous kvset for the second KVS tree. Here, a homogeneous kvset includes nodes from only one KVS tree. The KVS tree database also includes a first determinative mapping of entries between the base level and the subsequent level and a second determinative mapping of entries between subsequent levels.

Abstract: Systems and techniques for reducing probabilistic filter query latency are described herein. A query for a probabilistic filter that is stored on a first media may be received from a caller. In response to receiving the query, cached segments of the probabilistic filter stored on a second media may be obtained. Here, the probabilistic filter provides a set membership determination that is conclusive in a determination that an element is not in a set. The query may be executed on the cached segments resulting in a partial query result. Retrieval of remaining data of the probabilistic filter from the first media to the second media may be initiated without intervention from the caller. Here, the remaining data corresponds to the query and data that is not in the cached segment. The partial query results may then be returned to the caller.

Abstract: Systems and techniques for collecting and using merge tree garbage metrics are described herein. A kvset is created for a node in a KVS tree. Here, a set of kvset metrics for the kvset are computed as part of the node creation. The kvset is added to the node. The node is selected for a compaction operation based on a metric in the set of kvset metrics. The compaction operation is performed on the node.

Abstract: A KVS tree and operations thereon are described herein. A key-value set (kvset) is received to store in a key-value data structure on at least one machine readable medium. The kvset includes a mapping of unique keys to values with the keys and the values of the kvset being immutable. The key-value data structure is organized as a tree with nodes of the tree including a temporally ordered sequence of kvsets. The kvset, once received, is written to a sequence of kvsets of a root-node of the tree.

Abstract: Systems and techniques for stream selection from multi-stream storage devices. Notification of a KVS tree write request for a multi-stream storage device is received. The notification includes a KVS tree scope corresponding to data in the write request. A stream identifier (ID) is assigned to the write request based on the KVS tree scope and a stability value of the write request. The stream ID is returned to govern stream assignment to the write request, the stream assignment modifying a write operation of the multi-stream storage device.

Abstract: Systems and techniques for merge tree modifications for maintenance operations are described herein. A request for a KVS tree is received. Here, the KVS tree is a data structure including nodes and the nodes include a temporally ordered sequence of kvsets that store keys in sorted order. A parameter set for the KVS tree is received. The request is executed on the KVS tree by modifying operation of the KVS tree in accordance with the parameter.

Abstract: An electrical adapter having a manually retractable cable assembly where the electrical contacts of the retractable cable assembly are disposed along an axis of rotation to minimize the friction between the cable and contacts therein when the cable is extended and retracted. The electrical adapter includes a housing; an electrical plug assembly including an interchangeable module coupled to an adapter module, the interchangeable module having a plurality of prongs for receiving a first voltage when mated with an electrical receptacle, and a converter electrically coupled to the assembly for converting the first voltage into a second voltage; and a retractable cable assembly supported by the housing and electrically coupled to the converter.

Abstract: An electrical adapter having a manually retractable cable assembly where the electrical contacts of the retractable cable assembly are disposed along an axis of rotation to minimize the friction between the cable and contacts therein when the cable is extended and retracted. The electrical adapter includes a housing; an electrical plug assembly including an interchangeable module coupled to an adapter module, the interchangeable module having a plurality of prongs for receiving a first voltage when mated with an electrical receptacle, and a converter electrically coupled to the assembly for converting the first voltage into a second voltage; and a retractable cable assembly supported by the housing and electrically coupled to the converter.

Abstract: An electrical adapter is supported by a housing and includes an electrical plug assembly having an input for receiving a high voltage, a converter electrically coupled to the assembly for converting the high voltage to a low voltage, and a retractable cable assembly supported by the housing and electrically coupled to the converter. The retractable cable assembly includes a cable coupled at one end to an electrical plug for outputting the low voltage to the electrical device, and is enabled to retract the cable. In a preferred embodiment, the retractable cable assembly includes slots defined within a bore of a cable reel to support a pair of first interengageable electrical contacts coupled to the other end of the low voltage cable. These electrical contacts rotationally mate with a pair of second interengageable electrical contacts disposed along the axis of rotation within the retractable cable assembly. One of the first contacts includes a pair of edges defining a gap therein.