Sample Other Dimension
Table and Columns
FactX_Other_Dimension - Other dimension for FactX, which contains a collection of low-cardinality attributes that are applicable to FactX but are not appropriate for another dimension
Column / Alternative | Data Type / Comment | Description / Examples / Notes | FactX_Other_ Dimension_Key FactXOtherDimensionKey | SmallInt | Surrogate key arbitrary number that uniquely identifies a collection of low-cardinality attributes that are applicable to FactX. 1, 2, 3, ..., and 0 (for not applicable). This key is also a column in the FactX table where it relates a fact to a collection of low-cardinality attributes. |
| | | Loaded_Date_Time LoadedDateTime | TimeStamp | Date and time, in the current time zone, a row was first loaded into the data warehouse staging area. ... 2011-05-20 23:59:59, 2011-05-21 00:00:00, .... The
date and time retrieved from this column are those that were in effect
in the time zone of the retrieval when the statement that loaded the row
began to execute, even if the row was loaded in a different time zone. | Modified_Date_Time ModifiedDateTime | TimeStamp | Date and time, in the current time zone, a row was last modified in the data warehouse staging area. 0000-00-00 00:00:00, ... 2011-05-20 23:59:59, 2011-05-21 00:00:00, .... The
date and time retrieved from this column are those that were in effect
in the time zone of the retrieval when the statement that last modified
the row began to execute, even if the row was modified in a different
time zone. |
- It is likely that such a table would not be
needed with Infobright. Since the columns are of low-cardinality, they
would be massively compressed using Infobright's 'lookup' comment and
could probably be added to the relevant fact table, speeding queries,
while using very little additional storage space.
- Some
of the attributes in this dimension may be related to each other, in
some sense, while other attributes may be completely unrelated.
- This dimension is a type 1 slowly changing dimension, in that a history of changes to it is not maintained.
- Only
changes that are applicable to every fact to which an instance of this
dimension is related may be made to that instance. Thus, few, if any,
changes are made to instances of this dimension.
- This
type of dimension is sometimes called a "junk dimension" since it
contains an assortment of things that are not appropriate for another
holder, similar to a "junk drawer" in a kitchen cabinet. However, since
this type of dimension contains valuable information, we prefer not to
use the word "junk" to refer to it.
- When this type of dimension applies to a fact table named Transaction it would be named Transaction_Other_Dimension.
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