Create a Measure Using the PERIODROLLING Function in OBIEE
Time series functions provide the ability to compare business performance with previous time periods, allowing you to analyze data that spans multiple time periods.
Functions of OBIEE 11g
AGO function is a time series aggregation function that calculates the aggregated value from the current time back to a specified time period.
Time series functions operate on members of time dimensions which are at or below the level of the function. Because of this, one or more columns that uniquely identify members at or below the given level must be projected in the query. Alternatively, you can apply a filter to the query that specifies a single member at or below the given level.
If unsupported metrics are requested, NULL values are returned, and a warning entry is written to the nqquery.log file when the logging level equals three or above.
AGO functions can be nested if all the
AGO functions have the same level argument. You can nest exactly one
TODATE and multiple
AGO functions if they each have the same level argument.
AGO(<measure_expression>, <level>, <number of period>)
The TODATE function accumulates the measure from the beginning of the time series grain period to the current displayed query grain period.
ToDate aggregates a measure attribute from the beginning of a specified time period to the currently displayed time. For example, this function can calculate Year to Date sales.
If unsupported metrics are requested, NULL values will be returned, and a warning entry will be written to the NQQuery.log file when the logging level equals three or above.
A ToDate function may not be nested within another ToDate function.
You can nest exactly one ToDate and multiple Ago functions if they each have the same level argument.
The PERIODROLLING function does not have a time series grain; instead, you specify a start and end period in the function.
The PERIODROLLING function lets you perform an aggregation across a specified set of query grain periods, rather than within a fixed time series grain. The most common use is to create rolling averages.
PERIODROLLING(measure, x ,y [,hierarchy])
measure is the name of a measure column.
x is an integer that specifies the offset from the current time. Precede the integer with a minus sign (-) to indicate an offset into the past.
y specifies the number of time units over which the function will compute. To specify the current time, enter 0.
hierarchy is an optional argument that specifies the name of a hierarchy in a time dimension, such as
yr, mon, day, that you want to use to compute the time window. This option is useful when there are multiple hierarchies in a time dimension, or when you want to distinguish between multiple time dimensions.
If you want to roll back or forward the maximum possible amount, use the keyword
UNBOUND. For example, the function
, -UNBOUND, 0) sums over the period starting from the beginning of time until now.
You can combine
AGGREGATE AT functions to specify the level of the
PERIODROLLING function explicitly. For example, if the query level is the day, but you want to find the sum of the previous and current months, use the following:
SELECT year, month, day, PERIODROLLING(AGGREGATE(sales AT month), -1)
PERIODROLLING(monthly_sales, -1, 1)
PERIODROLLING(monthly_sales, -UNBOUND, 2)
PERIODROLLING(monthly_sales, -UNBOUND, UNBOUND)
Determining the Level Used by the PERIODROLLING Function
The unit of time (offset) used in the
PERIODROLLING function is called the level of the function. This value is determined by the measure level of the measures in its first argument and the query level of the query to which the function belongs. The measure level for the measure can be set in the Administration Tool. If a measure level has been set for the measure used in the function, the measure level is used as the level of the function. The measure level is also called the storage grain of the function.
If a measure level has not been set in the Administration Tool, then the query level is used. The query level is also called the query grain of the function. In the following example, the query level is month, and the
PERIODROLLING function computes the sum of the last, current, and next month for each city for the months:
SELECT year, month, country, city, PERIODROLLING(sales, -1, 1)
WHERE month in ('Mar', 'Apr') AND city = 'New York'
When there are multiple hierarchies in the time dimension, you must specify the
hierarchy argument in the
SELECT year, fiscal_year, month, PERIODROLLING(sales, -1, 1, "fiscal_time_hierarchy")
In this example, the level of the
PERIODROLLING function is
Create a Measure Using the PERIODROLLING Function in OBIEE
-Right-click the F1 Revenue logical table and select New Object > Logical Column.
-On the General tab, name the new logical column Revenue 3-Period Rolling Sum.
-On the Column Source tab, select "Derived from existing columns using an expression."
-Open the Expression Builder.
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-Select Functions > Time Series Functions and double-click PeriodRolling to insert the expression.
-Click <<Measure>> in the expression.
-Select Logical Tables > F1 Revenue and then double-click Revenue to add it to the expression.
-Click <<Starting Period Offset>> in the expression.
-Enter -2. This identifies the first period in the rolling aggregation.
-Click <<Ending Period Offset>>.
-Enter 0. This identifies the last period in the rolling aggregation.
These integers are the relative number of periods from a displayed period. In this example, if the query grain is a month, the 3 month rolling sum starts two months in the past (-2) and includes the current month (0).
-Click OK to close the Expression Builder.
-Check your work in the Logical Column dialog box:
-Click OK to close the Logical Column dialog box.
-Drag the Revenue 3-Period Rolling Sum logical column to the Base Facts presentation folder.
-Save the repository and check consistency. Fix any errors or warnings before you proceed.
-Close the repository. Leave the Administration Tool open.
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