什么是OLAP

ADVERTISING EXPENSE = (PRODUCT A SALES/TOTAL CORPORATION PRODUCT A SALES) * ADVERTISING EXPENSE FOR PRODUCT A FOR BUSINESS UNIT XYZ

Two members of a hierarchy have the same generation if they have the same number of ancestors leading to the top. For example, the top member of a dimension is from Generation 1. There may be two or more members in Generation 1 if there are multiple hierarchies in the dimension.
NOTE: The terms generation and level are both necessary to describe sub-groups of dimension members, since, for example, although two siblings share the same parent and are therefore of the same generation, they won't be from the same level if one of the siblings has a child and the other doesn't.
Synonyms: Peer, Sibling
See: Level, Hierarchical Relationships, Parent, Children

Any dimension's members may be organized based on parent-child relationships, typically where a parent member represents the consolidation of the members which are its children. The result is a hierarchy, and the parent/child relationships are hierarchical relationships.

See: Page Display

See: Cube, Array, Multi-dimensional

Input members have values that are loaded directly from either manual entry or by accessing another computer-based data source, as opposed to being calculated from the raw data.

Members of a dimension with hierarchies are at the same level if, within their hierarchy, they have the same maximum number of descendants in any single path below. For example, in an Accounts dimension which consists of general ledger accounts, all of the detail accounts are Level 0 members. The accounts one level higher are Level 1, their parents are Level 2, etc. It can happen that a parent has two or more children which are different levels, in which case the parent's level is defined as one higher than the level of the child with the highest level.
See: Generation, Hierarchical

A dimension member is a discrete name or identifier used to identify a data item's position and description within a dimension. For example, January 1989 or 1Qtr93 are typical examples of members of a Time dimension. Wholesale, Retail, etc., are typical examples of members of a Distribution Channel dimension.
Synonyms: Position, Item, Attribute

A member combination is an exact description of a unique cell in a multi-dimensional array, consisting of a specific member selection in each dimension of the array.
See: Cell

A special data item which indicates that the data in this cell does not exist. This may be because the member combination is not meaningful (e.g., snowmobiles may not be sold in Miami) or has never been entered. Missing data is similar to a null value or N/A, but is not the same as a zero value.

See: Array, Multi-dimensional

A computer language that allows one to specify which data to retrieve out of a cube. The user process for this type of query is usually called slicing and dicing. The result of a multi-dimensional query is either a cell, a two-dimensional slice, or a multi-dimensional sub-cube.

Navigation is a term used to describe the processes employed by users to explore a cube interactively by drilling, rotating and screening, usually using a graphical OLAP client connected to an OLAP server.

Nesting is a display technique used to show the results of a multi-dimensional query that returns a sub-cube, i.e., more than a two-dimensional slice or page. The column/row labels will display the extra dimensionality of the output by nesting the labels describing the members of each dimension. For example, the display's columns may be:
January February March Actual Budget Actual Budget Actual Budget Prod A Prod B Prod A Prod B Prod A Prod B Prod A Prod B Prod A Prod B Prod A Prod B
These columns contain three dimensions, nested in the user's preferred arrangement. Likewise, a report's rows may contain nested dimensions:
Chocolate Bars Unit Sales xxxx xxxx xxxx Revenue xxxx xxxx xxxx Margin xxxx xxxx xxxx Fruit Bars Unit Sales xxxx xxxx xxxx Revenue xxxx xxxx xxxx Margin xxxx xxxx xxxx

Data which exists and has values, as opposed to null or missing data.

End user applications that can request slices from OLAP servers and provide two- dimensional or multi-dimensional displays, user modifications, selections, ranking, calculations, etc., for visualization and navigation purposes. OLAP clients may be as simple as a spreadsheet program retrieving a slice for further work by a spreadsheet- literate user or as high-functioned as a financial modeling or sales analysis application.

A page dimension is generally used to describe a dimension which is not one of the two dimensions of the page being displayed, but for which a member has been selected to define the specific page requested for display. All page dimensions must have a specific member chosen in order to define the appropriate page for display.

The page display is the current orientation for viewing a multi-dimensional slice. The horizontal dimension(s) run across the display, defining the column dimension(s). The vertical dimension(s) run down the display, defining the contents of the row dimension(s). The page dimension-member selections define which page is currently displayed. A page is much like a spreadsheet, and may in fact have been delivered to a spreadsheet product where each cell can be further modified by the user.

The member that is one level up in a hierarchy from another member. The parent value is usually a consolidation of all of its children's values.
See: Children

See: Rotate

Pre-calculated data is data in output member cells that are computed prior to, and in anticipation of, ad-hoc requests. Pre-calculation usually results in faster response to queries at the expense of storage. Data that is not pre-calculated must be calculated at query time.
See: Derived Data/Members, Output Data

Reach through is a means of extending the data accessible to the end user beyond that which is stored in the OLAP server. A reach through is performed when the OLAP server recognizes that it needs additional data and automatically queries and retrieves the data from a data warehouse or OLTP system.

See: Consolidate

To change the dimensional orientation of a report or page display. For example, rotating may consist of swapping the rows and columns, or moving one of the row dimensions into the column dimension, or swapping an off-spreadsheet dimension with one of the dimensions in the page display (either to become one of the new rows or columns), etc. A specific example of the first case would be taking a report that has Time across (the columns) and Products down (the rows) and rotating it into a report that has Product across and Time down. An example of the second case would be to change a report which has Measures and Products down and Time across into a report with Measures down and Time over Products across. An example of the third case would be taking a report that has Time across and Product down and changing it into a report that has Time across and Geography down.
Synonym: Pivot

See: Page Display

Restricting the view of database objects to a specified subset. Further operations, such as update or retrieve, will affect only the cells in the specified subset. For example, scoping allows users to retrieve or update only the sales data values for the first quarter in the east region, if that is the only data they wish to receive.

A selection is a process whereby a criterion is evaluated against

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