Time Series Functions in OBIEE

Time series functions operate on time-oriented dimensions. The time series functions calculate AGO, TODATE, and PERIODROLLING functions based on user supplied calendar tables, not on standard SQL date manipulation functions.

These functions let you use Expression Builder to call a logical function to perform time series calculations instead of aliasing physical tables and modeling logically.

To use time series functions on a particular dimension, you must designate the dimension as a Time dimension and set one or more keys at one or more levels as chronological keys.

Functions include:

·         AGO

·         PERIODROLLING

·         TODATE

In this topic you create time series calculation measures using Oracle BI time series functions.

Time series functions include AGO, TODATE, and PERIODROLLING. These functions let you use Expression Builder to call a logical function to perform time series calculations instead of creating aliases for physical tables and modeling logically. The time series functions calculate AGO, TODATE, and PERIODROLLING functions based on the calendar tables in your data warehouse, not on standard SQL date manipulation functions.

To create time series measures, you perform the following steps:
• Identify a Logical Dimension as a Time Dimension
• Identify Level Keys as Chronological Keys
• Create a Measure Using the AGO Function
• Create a Measure Using the TODATE Function
• Create a Measure Using the PERIODROLLING Function
• Test Your Work

Time Series Functions in OBIEE

1) Ago

Ago is a time series function that calculates the aggregated value from the current time back to a specified time period. this is useful for comparison  such as amount compared to amount a month ago.

Syntax:  AGO(<Measure >,<Level>,<number of period>)

Measure: A measure column.

Level: On which level you want to calculate this measure such as Year,Quarter,Month etc.

Number of period: how many level you want to go back from current time such as 2 year back,2 months back etc.

Example : AGO(Amount,Year,1) this will give the last year amount .

2) ToDate 

To Date is a time series function that calculates a measure attributes from the beginning of a specified time period to the currently displayed time period.

Syntax : ToDate(<Measure>,<Level>)

Measure: A measure column.

Level: On which level you want to calculate this measure such as Year,Quarter,Month etc.

Example : ToDate(Amount,Year) this will give the amount from the beginning of the year to Currently displayed time.

3) Period Rolling

Period Rolling is a new time series function in 11g .It computes the sum of a measure over the period starting x units of time and ending y units of time from the current time .This function allow us to create a aggregated measures across a specified set of query grain period rather than within a fixed time series grain.

Syntax: PeriodRolling(<Measure>,<Starting Period Offset>, < Starting Period Offset>)

Measure: A measure column.

Starting Period Offset: Starting period used in rolling aggregation.

Ending Period Offset: Ending period used in rolling aggregation.

Example : PeriodRolling(Amount,-2,0) this will give three months rolling sum of column Amount.It includes past two months with the current month. Numerical value -2 indicates May-14,Jun-14 if current month is Jul-14.Numerical value 0 indicates current month.

Note : This function has no time series grain ,the length of the rolling sequence is determined by query grain for example it will give the last three Monthamount if the query grain is month , if the query grain is year then it will give last three Year Amount.