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Column Families
A column family is a database object that contains columns of related data. It is a tuple (pair) that consists of a attribute–value pair, key–value pair, where the key is mapped to a value that is a set of columns. In analogy with relational databases, a column family is as a "table", each key-value pair being a "row". Each column is a tuple (triplet (other), triplet) consisting of a column name, a value, and a timestamp. In a relational database, relational database table, this data would be grouped together within a table with other non-related data. Two types of column families exist: * Standard column family: contains only columns * Super column family: contains a map of super columns See also * Keyspace (NoSQL) References {{reflist External linksThe Apache Cassandra data model Distributed data stores NoSQL ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database Object
A database object is a structure for storing, Database administrator, managing and presenting application- or user-specific data in a database. Depending on the database management system (DBMS), many different types of database objects can exist. The following is a list of the most common types of database objects found in most relational databases (RDBMS): * Tablespace, storage space for tables in a database * Table (database), Tables, a set of values organized into rows and columns * Database index, Indexes, a data structure providing faster queries (at the expense of slower writing and storage to maintain the index structure) * View (SQL), Views, a virtual table that is made as it is queried * Synonym (database), Synonyms, alternate names for a table, view, sequence or other object in a database * Stored procedures and user-defined functions * Database trigger, Triggers, procedures which are run automatically based on specific events * Database constraint, Constraints, a constr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tuple
In mathematics, a tuple is a finite sequence or ''ordered list'' of numbers or, more generally, mathematical objects, which are called the ''elements'' of the tuple. An -tuple is a tuple of elements, where is a non-negative integer. There is only one 0-tuple, called the ''empty tuple''. A 1-tuple and a 2-tuple are commonly called a singleton and an ordered pair, respectively. The term ''"infinite tuple"'' is occasionally used for ''"infinite sequences"''. Tuples are usually written by listing the elements within parentheses "" and separated by commas; for example, denotes a 5-tuple. Other types of brackets are sometimes used, although they may have a different meaning. An -tuple can be formally defined as the image of a function that has the set of the first natural numbers as its domain. Tuples may be also defined from ordered pairs by a recurrence starting from an ordered pair; indeed, an -tuple can be identified with the ordered pair of its first elements and its t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triplet (other)
A triplet is a set of three items. It may refer to: Science * A series of three nucleotide bases forming an element of the Genetic code * J-coupling as part of Nuclear magnetic resonance spectroscopy * Opal in preparation to be a gemstone * Spin triplet in quantum mechanics, as in triplet oxygen, or triplet state in general * Tuple of length 3 in mathematics Technologies * Photography triplet, or paint triplet * Triplet lens, an optical device consisting of three single lenses * Tandem bicycle, with three seats Other uses * Triplets, the multiple birth of three children * Triplet Lakes, a group of lakes in Minnesota * ''The Triplets'', a Spanish children's book * The Triplets (band), a Latin pop group * Binghamton Triplets, a minor league baseball team * A triplet, a kind of assembled gem * In music, a tuplet of three successive notes of equal duration * "The Triplets", Tyler Johnson, Ondrej Palat, and Nikita Kucherov#Early years, "The Triplets" era (2013–2015), Nikita Kucherov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timestamp
A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second. Timestamps do not have to be based on some absolute notion of time, however. They can have any epoch, can be relative to any arbitrary time, such as the power-on time of a system, or to some arbitrary time in the past. A distinction is sometimes made between the terms datestamp, timestamp and date-timestamp: * Datestamp or DS: A date, for example -- according to ISO 8601 * Timestamp or TS: A time of day, for example :: using 24-hour clock * Date-timestamp or DTS: Date and time, for example --, :: History The term "timestamp" derives from rubber stamps used in offices to stamp the current date, and sometimes time, in ink on paper documents, to record when the document was received. Common examples of this type of timestamp are a postmark on a letter or the "in" and "out" times on a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Relational Database
A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured format using rows and columns. Many relational database systems are equipped with the option of using SQL (Structured Query Language) for querying and updating the database. History The concept of relational database was defined by E. F. Codd at IBM in 1970. Codd introduced the term ''relational'' in his research paper "A Relational Model of Data for Large Shared Data Banks". In this paper and later papers, he defined what he meant by ''relation''. One well-known definition of what constitutes a relational database system is composed of Codd's 12 rules. However, no commercial implementations of the relational model conform to all of Codd's rules, so the term has gradually come to describe a broader class of database systems, which at a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database Table
In a database, a table is a collection of related data organized in table format; consisting of columns and rows. In relational databases, and flat file databases, a ''table'' is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. A table has a specified number of columns, but can have any number of rows. Each row is identified by one or more values appearing in a particular column subset. A specific choice of columns which uniquely identify rows is called the primary key. "Table" is another term for "relation"; although there is the difference in that a table is usually a multiset (bag) of rows where a relation is a set and does not allow duplicates. Besides the actual data rows, tables generally have associated with them some metadata, such as constraints on the table or on the values within particular columns. The data in a table does not have to be physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Column Family
The standard column family is a NoSQL object that contains columns of related data. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that is a set of columns. In analogy with relational databases, a standard column family is as a "table", each key–value pair being a "row". Each column is a tuple ( triplet) consisting of a column name, a value, and a timestamp. In a relational database table, this data would be grouped together within a table with other non-related data. Standard column families are column containers sorted by their names can be referenced and sorted by their row key. Benefits Accessing the data in a distributed data store would be expensive (time-consuming), if it would be saved in form of a table. It would also be inefficient to read all column families that would make up a row in a relational table and put it together to form a row, as the data for it is distributed on a large number of nodes. Therefore, the user ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super Column Family
A super column family is a NoSQL object that contains column families. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that are column families. In analogy with relational databases, a super column family is something like a "view" on a number of tables. It can also be seen as a map of tables. Benefits It is useful when making a data model to have some kind of a view on a number of tables. Using a super column family is something similar to that in distributed data stores. There are, however, no "joins" between the "tables", as data stores like Apache Cassandra are non-relational. Sorting and querying There is no way to sort super columns after they have been inserted, nor to query an arbitrary query in distributed data stores. Super columns are sorted when they are added to the column family, and it is also possible to use a different sorting attribute for the contained columns of a super column. Similar to the standard column fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super Column
A super column is a tuple (a pair) with a binary super column name and a value that maps it to many columns. They consist of a key–value pairs, where the values are columns. Theoretically speaking, super columns are ( sorted) associative array of columns. Similar to a regular column family where a row is a sorted map of column names and column values, a row in a super column family is a sorted map of super column names that maps to column names and column values. A super column is part of a keyspace together with other super columns and column families, and columns. Code example Written in the JSON-like syntax, a super column definition can be like this: Where: "databases" are keyspace; "Cassandra" and "HBase" are rowKeys; "name" and "address" are ''super column'' names; "firstName", "city", "age", etc. are column names. See also * Column (data store) * Keyspace (distributed data store) * Super column family A super column family is a NoSQL object that contains c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keyspace (NoSQL)
A keyspace (or key space) in a NoSQL data store is an object that holds together all column families of a design. It is the outermost grouping of the data in the data store. It resembles the schema concept in Relational database management systems. Generally, there is one keyspace per application. Structure A keyspace may contain column families or super columns. Each super column contains one or more column families, and each column family contains at least one column. The keyspace is the highest abstraction in a distributed data store. This is fundamental in preserving the structural heuristics in dynamic data retrieval. Multiple relay protocol algorithms are integrated within the simple framework. Comparison with relational database systems The keyspace has similar importance like a schema has in a database. In contrast to the schema, however, it does not stipulate any concrete structure, like it is known in the entity–relationship model used widely in the relational data mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Data Stores
Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations *Probability distribution, the probability of a particular value or value range of a variable **Cumulative distribution function, in which the probability of being no greater than a particular value is a function of that value *Frequency distribution, a list of the values recorded in a sample * Inner distribution, and outer distribution, in coding theory *Distribution (differential geometry), a subset of the tangent bundle of a manifold * Distributed parameter system, systems that have an infinite-dimensional state-space *Distribution of terms, a situation in which all members of a category are accounted for *Distributivity, a property of binary operations that generalises the distributive law from elementary algebra *Distribution (number theory) *Distribution problems, a common type of problems in combinatorics where the goal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
