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: 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: 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: 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: 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: 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: Aspects of the present disclosure provide for operations for a tree data structure that provides order-based node traversal. For some embodiments, the tree data structure stores one or more key-value pairs, implements at least one linked-list data structure, and enables traversal of nodes within the tree data structure based on a key order (e.g., forward or reverse key order).

Abstract: Aspects of the present disclosure provide for operations of a key-value store (KVS) that uses journaling with storage of data (e.g., key data or value data of a key-value pair) in different types of data storage objects (e.g., data storage formats) selected based on one or more criteria.

Abstract: Aspects of the present disclosure provide various embodiments for selective use of a portion of a key, such as a prefix of the key (also referred to as a key prefix of a key), with respect to a key-value store (KVS) tree data structure, such as when storing a key-value pair (associated with the key) within the KVS tree data structure or navigating through the KVS tree data structure. For some embodiments, when navigating a KVS tree based on a key, a first set of levels (e.g., a first series of levels) of the KVS tree is navigated by a first portion (e.g., a prefix) of the key, and a second set of levels (e.g., a second series of levels) of the KVS tree is navigated by a second portion (e.g., an entire portion) of the key.

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: Aspects of the present disclosure provide for operations of a key-value tree data structure that merges key-value pair data of a node, in a key-value tree data structure using counter values.

Abstract: Aspects of the present disclosure provide for operations of a key-value tree data structure that: merge key-value sets within a given node by merging and rewriting key blocks of the key-value sets while rewriting or deferring rewrite of value blocks of the merged key-value sets based on whether one or more child nodes of the given node comprise a leaf node; and move one or more portions of the merged key-value set into one or more child nodes of the given node.

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: An apparatus for launching a ball is disclosed. An embodiment of the apparatus includes a ball launching unit including a port for ejecting a ball and a support for supporting the ball launching unit. The ball launching unit is pivotably coupled to the support to permit angular adjustment of the ball launching unit about a horizontal axis of rotation to vary a launch angle of an ejected ball, and wherein the horizontal axis of rotation intersects the port.

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.