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  2. Fold (higher-order function) - Wikipedia

    en.wikipedia.org/wiki/Fold_(higher-order_function)

    In functional programming, fold (also termed reduce, accumulate, aggregate, compress, or inject) refers to a family of higher-order functions that analyze a recursive data structure and through use of a given combining operation, recombine the results of recursively processing its constituent parts, building up a return value.

  3. Aggregate function - Wikipedia

    en.wikipedia.org/wiki/Aggregate_function

    Common aggregate functions include: Average (i.e., arithmetic mean) Count; Maximum; Median; Minimum; Mode; Range; Sum; Others include: Nanmean (mean ignoring NaN values, also known as "nil" or "null") Stddev; Formally, an aggregate function takes as input a set, a multiset (bag), or a list from some input domain I and outputs an element of an ...

  4. Aggregate (data warehouse) - Wikipedia

    en.wikipedia.org/wiki/Aggregate_(data_warehouse)

    This complexity should be transparent to the users of the data warehouse, thus when a request is made, the data warehouse should return data from the table with the correct grain. So when requests to the data warehouse are made, aggregate navigator functionality should be implemented, to help determine the correct table with the correct grain.

  5. Slowly changing dimension - Wikipedia

    en.wikipedia.org/wiki/Slowly_changing_dimension

    Transactions that reference a particular surrogate key (Supplier_Key) are then permanently bound to the time slices defined by that row of the slowly changing dimension table. An aggregate table summarizing facts by supplier state continues to reflect the historical state, i.e. the state the supplier was in at the time of the transaction; no ...

  6. Comparison of OLAP servers - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_OLAP_servers

    The following tables compare general and technical information for a number of online analytical processing (OLAP) servers. Please see the individual products articles for further information. Please see the individual products articles for further information.

  7. Table (database) - Wikipedia

    en.wikipedia.org/wiki/Table_(database)

    Views also function as relational tables, but their data are calculated at query time. External tables (in Informix [3] or Oracle, [4] [5] for example) can also be thought of as views. In many systems for computational statistics, such as R and Python's pandas, a data frame or data table is a data type supporting the table

  8. Window function (SQL) - Wikipedia

    en.wikipedia.org/wiki/Window_function_(SQL)

    In SQL, a window function or analytic function [1] is a function which uses values from one or multiple rows to return a value for each row. (This contrasts with an aggregate function, which returns a single value for multiple rows.) Window functions have an OVER clause; any function without an OVER clause is not a window function, but rather ...

  9. Function application - Wikipedia

    en.wikipedia.org/wiki/Function_application

    Function application can be trivially defined as an operator, called apply or $, by the following definition: $ ⁡ = The operator may also be denoted by a backtick (`).. If the operator is understood to be of low precedence and right-associative, the application operator can be used to cut down on the number of parentheses needed in an expression.