About Database Restructuring
As your business changes, you change the Essbase database outline to capture new product lines, provide information on new scenarios, reflect new time periods, and so on. Some changes to a database outline affect the data storage arrangement, requiring Essbase to restructure the database.
Because changes that require restructuring the database can be time-consuming (unless you discard the data before restructuring), consider deciding on such changes based on how they affect performance.
Restructuring an Essbase cube results in a temporary increase (double at most) of the index and data cache sizes. When the restructure is completed, both the index and data cache return to the sizes they were before the restructure was performed.Note:
For information about clearing data and thus avoiding some restructuring, see CLEARDATA and CLEARBLOCK calculation commands.
Implicit Restructures
Essbase initiates an implicit restructure of the database files after an outline is changed using Outline Editor or Dimension Build. The type of restructure that is performed depends on the type of changes made to the outline.
Dense restructure: If a member of a dense dimension is moved, deleted, or added, Essbase restructures the blocks in the data files and creates new data files. When Essbase restructures the data blocks, it regenerates the index automatically so that index entries point to the new data blocks. Empty blocks are not removed. Essbase marks all restructured blocks as dirty, so after a dense restructure you must recalculate the database. Dense restructuring, the most time-consuming of the restructures, can take a long time to complete for large databases.
Sparse restructure: If a member of a sparse dimension is moved, deleted, or added, Essbase restructures the index and creates new index files. Restructuring the index is relatively fast; the time required depends on the index size.
Outline-only restructure: If a change affects only the database outline, Essbase does not restructure the index or data files. Member name changes, creation of aliases, and dynamic calculation formula changes are examples of changes that affect only the database outline.
Note:
How a database outline is changed (by using Outline Editor or using dimension build) does not influence restructuring. Only the type of information change influences what type of restructuring, if any, takes place. For information about outline changes and the type of restructures they cause, see Outline Change Quick Reference.
Explicit Restructures
When you purposefully initiate an Essbase database restructure, it's an explicit restructure. An explicit restructure forces a full restructure of the database. A full restructure is a dense restructure, plus removal of empty blocks. All data load and calculation transaction history is removed after an explicit restructure.
To initiate an full restructure, you can use the MaxL statement alter database force restructure.
Conditions Affecting Database Restructuring
Use of Intelligent Calculation, member name changes, and formula changes can affect Essbase database restructuring.
If you use Intelligent Calculation, all restructured blocks are marked as dirty whenever data blocks are restructured. Marking the blocks as dirty forces the next default Intelligent Calculation to be a full calculation.
If you change a name or a formula, Essbase does not mark the affected blocks as dirty. If Intelligent Calculation is on, default calculations do not recalculate these affected members. You must explicitly re-calculate them.
Changes to attribute dimensions do not trigger a restructure.
Refer to the following topics for more information:
Table 32-1 Topics Related To Database Restructuring
| Topic | Related Information |
|---|---|
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Intelligent Calculation |
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Sparse and dense dimensions |
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Attribute dimensions |
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Dimension building |
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Outline Editor |