diff --git a/docs/glossary.md b/docs/glossary.md index 4607973e9..2d56bcbd3 100644 --- a/docs/glossary.md +++ b/docs/glossary.md @@ -6,50 +6,50 @@ nav = [] ## Glossary -[Index](../data-model/#index): An Index is a top level container in Pilosa, analogous to a database in an RDBMS. Queries cannot operate across multiple indexes. +[Anti-entropy](../configuration/#anti-entropy-interval): A periodic process that compares each [slice](#slice) and its [replicas](#replica) across the [cluster](#cluster) to repair inconsistencies. -[Column](../data-model/#column): Columns are the fundamental horizontal data axis within Pilosa. Columns are global to all [frames](#frame) within an [index](#index). - -[Row](../data-model/#row): Rows are the fundamental vertical data axis within Pilosa. They are namespaced to each [frame](#frame) within an [index](#index). Represented as a [bitmap][#bitmap]. +[Attribute](../data-model/#attribute): Attributes can be associated to both [rows](#row) and [columns](#column). This metadata is kept separately from the core binary matrix in a [BoltDB](https://github.com/boltdb/bolt) store. [Bit](../data-model/#overview): Bits are the fundamental unit of data in Pilosa. A bit lives in a [frame](#frame), at the intersection of a [row](#row) and [column](#column). [Bitmap](../data-model/#overview): The on-disk and in-memory representation of a [row](#row). Implemented with [Roaring](#roaring-bitmap). -[Roaring Bitmap](http://roaringbitmap.org): the compressed bitmap format which Pilosa uses to [implement bitmaps](../architecture/#roaring-bitmap-storage-format), for both storage and logical query operations. +Cluster: A cluster consists of one or more [nodes](#node) which share a cluster configuration. The cluster also defines how data is [replicated](#replica) throughout and how internode communication is coordinated. Pilosa does not have a leader node, all data is evenly distributed, and any node can respond to queries. -[Attribute](../data-model/#attribute): Attributes can be associated to both [rows](#row) and [columns](#column). This metadata is kept separately from the core binary matrix in a [BoltDB](https://github.com/boltdb/bolt) store. +[Column](../data-model/#column): Columns are the fundamental horizontal data axis within Pilosa. Columns are global to all [frames](#frame) within an [index](#index). -[PQL](../query-language/): Pilosa Query Language. +Fragment: A Fragment is the intersection of a [frame](#frame) and a [slice](#slice) in an [index](#index). [Frame](../data-model/#frame): Frames are used to group [rows](#row) into different categories. `RowID`s are namespaced by frame such that the same `RowID` in a different frame refers to a different row. For [ranked](#topn) frames, rows are kept in sorted order within the frame. -[View](../data-model/#view): Views separate the different data layouts within a [Frame](#frame). The two primary views are standard and inverse which represent the typical [row](#row)/[column](#column) data and its inverse respectively (an [inverted index](https://en.wikipedia.org/wiki/Inverted_index), or a matrix transpose). Time based frame views are automatically generated for each time quantum. Views are internally managed by Pilosa, and never exposed directly via the API. This simplifies the functional interface by separating it from the physical data representation. +[Index](../data-model/#index): An Index is a top level container in Pilosa, analogous to a database in an RDBMS. Queries cannot operate across multiple indexes. -Fragment: A Fragment is the intersection of a [frame](#frame) and a [slice](#slice) in an [index](#index). +[Jump Consistent Hash](https://arxiv.org/pdf/1406.2294v1.pdf): A fast, minimal memory, consistent hash algorithm that evenly distributes the workload even when the number of buckets changes. + +MaxSlice: The total number of [slices](#slice) allocated to handle the current set of [columns](#columns). This value is important for all [nodes](#node) to efficiently distribute queries. + +Node: An individual running instance of Pilosa server which belongs to a [cluster](#cluster). + +Partition: The [consistent hash](#jump-consistent-hash) maps keys to partitions (or locations on the unit circle), based on a preset maximum number of partitions (256 by default). Partitions are then evenly mapped to physical [nodes](#node). To add nodes to the [cluster](#cluster), the partitions must be remapped, and data is then associated across the new cluster topology. + +[PQL](../query-language/): Pilosa Query Language. + +[Protobuf](https://developers.google.com/protocol-buffers/): Protocol Buffers is a binary serialization format which Pilosa uses for internal messages, and can be used by clients as an alternative to JSON. + +[Replica](../configuration/#cluster-replicas): A copy of a [fragment](#fragment) on a different [node](#node) than the original. The `cluster.replicas` configuration parameter determines how many replicas of a fragment exist in the cluster. This includes the original, so a value of 1 means no extra copies are made. + +[Roaring Bitmap](http://roaringbitmap.org): the compressed bitmap format which Pilosa uses to [implement bitmaps](../architecture/#roaring-bitmap-storage-format), for both storage and logical query operations. + +[Row](../data-model/#row): Rows are the fundamental vertical data axis within Pilosa. They are namespaced to each [frame](#frame) within an [index](#index). Represented as a [bitmap][#bitmap]. [Slice](../data-model/#slice): [Columns](#column) are sharded on a preset [width](#slicewidth). Each shard is referred to as a slice in Pilosa. Slices are operated on in parallel and are evenly distributed across the cluster via a [consistent hash](#jump-consistent-hash). SliceWidth: This is the number of [columns](#column) in a [slice](#slice). By default, 220 or about one million. -MaxSlice: The total number of [slices](#slice) allocated to handle the current set of [columns](#columns). This value is important for all [nodes](#node) to efficiently distribute queries. - -[Anti-entropy](../configuration/#anti-entropy-interval): A periodic process that compares each [slice](#slice) and its [replicas](#replica) across the [cluster](#cluster) to repair inconsistencies. - -Node: An individual running instance of Pilosa server which belongs to a [cluster](#cluster). - -Cluster: A cluster consists of one or more [nodes](#node) which share a cluster configuration. The cluster also defines how data is [replicated](#replica) throughout and how internode communication is coordinated. Pilosa does not have a leader node, all data is evenly distributed, and any node can respond to queries. - -TopN: A [PQL](#pql) query that returns a list of `RowID`s, sorted by the count of [bits](#bit) set in the [row](#row), within a specified [frame](#frame). - [Tanimoto](../examples/#chemical-similarity-search): Used for similarity queries on Pilosa data. The [Tanimoto Coefficient](https://en.wikipedia.org/wiki/Jaccard_index#Tanimoto_similarity_and_distance) between two [bitmaps](#bitmap) A and B is the ratio of the size of their intersection to the size of their union (|A∩B|/|A∪B|). -[Protobuf](https://developers.google.com/protocol-buffers/): Protocol Buffers is a binary serialization format which Pilosa uses for internal messages, and can be used by clients as an alternative to JSON. - [TOML](https://github.com/toml-lang/toml): the language used for Pilosa's [configuration file](../configuration). -[Jump Consistent Hash](https://arxiv.org/pdf/1406.2294v1.pdf): A fast, minimal memory, consistent hash algorithm that evenly distributes the workload even when the number of buckets changes. +TopN: A [PQL](#pql) query that returns a list of `RowID`s, sorted by the count of [bits](#bit) set in the [row](#row), within a specified [frame](#frame). -Partition: The [consistent hash](#jump-consistent-hash) maps keys to partitions (or locations on the unit circle), based on a preset maximum number of partitions (256 by default). Partitions are then evenly mapped to physical [nodes](#node). To add nodes to the [cluster](#cluster), the partitions must be remapped, and data is then associated across the new cluster topology. - -[Replica](../configuration/#cluster-replicas): A copy of a [fragment](#fragment) on a different [node](#node) than the original. The `cluster.replicas` configuration parameter determines how many replicas of a fragment exist in the cluster. This includes the original, so a value of 1 means no extra copies are made. +[View](../data-model/#view): Views separate the different data layouts within a [Frame](#frame). The two primary views are standard and inverse which represent the typical [row](#row)/[column](#column) data and its inverse respectively (an [inverted index](https://en.wikipedia.org/wiki/Inverted_index), or a matrix transpose). Time based frame views are automatically generated for each time quantum. Views are internally managed by Pilosa, and never exposed directly via the API. This simplifies the functional interface by separating it from the physical data representation.