Summary functions

Default summary

Depending on the type of data item, applies the function None, Summarize, or Calculated based on the context in which the data item appears. This is the default function.

Calculated is applied if the underlying data source is OLAP. It is also applied in the following situations:

• When the data item expression contains a summary function
• When the data item expression is an if then else or case expression that contains a reference to at least a modeled measure in its condition
• When the data item expression contains a reference to a model calculation or to a measure that has the Regular Aggregate property set to a value other than Unsupported
• When the data item expression contains a reference to at least one data item that has the Summary aggregation property set to a value other than None

If the underlying data source is relational and if the data item expression contains no summary functions and a reference to at least one fact that has the Regular Aggregate property set to a value other than Unsupported, Summarize is applied.

If the underlying data source is OLAP and if the data item expression contains no summary functions and a reference to at least one fact that has the Regular Aggregate property set to a value other than Unsupported, Calculated is applied.

If the underlying data source is SAP BW, reports containing aggregations and summaries run more efficiently if the aggregation applied to a query item matches the aggregation rule for the underlying key figure on the SAP BW server. In Cognos Analytics - Reporting, the easiest way to accomplish this is to change the value of the Detail aggregation property to Default.

In all other contexts, None is applied.

For relational and dimensionally modeled relational (DMR) data sources, if this function is applied to a data item expression that has the average function, weighted averages are computed based on the lowest level detail values in the data source.

Average

Adds all existing values and then divides by the count of existing values.

Calculated

Specifies that all the terms within the expression for a data item are aggregated according to their own rollup rules, and then the results of those aggregations are computed within the overall expression.

For example, a list contains the data item Quantity with the Detail aggregation property set to Total. You add a query calculation named Quantity Calculated. You define its expression as Quantity + 100 and you set its Detail aggregation property to Calculated. When you run the report, the values for Quantity Calculated are computed by first adding all values for Quantity and then adding 100 to each value.

Count

Counts all existing values.

If the underlying data source is dimensionally modeled relational (DMR), Count behaves as described in the following table if it is specified in the Detail aggregation or Summary aggregation property for a data item.

If you add the count summary to a non-fact column in a list and then group the column, the column will not be grouped when you run the report. To resolve this issue, group the column first before adding the count summary.

Count distinct

Returns the total number of unique non-null records.

If the underlying data source is OLAP, count distinct behaves as described in the following table if it is specified in the Summary aggregation property for a data item.

If the underlying data source is dimensionally modeled relational (DMR), count distinct is supported for levels, member sets, attributes, and measures when it is specified in the Detail aggregation or Summary aggregation property for a data item.

Custom

Summarizes data based on an expression that you define.

Maximum

Selects the largest existing value.

Median

Returns the median value of the selected data item.

Minimum

Selects the smallest existing value.

None

Does not aggregate values.

If the underlying data source is relational, the data item is grouped when the query property Auto group & summarize is set to Yes.

Not Applicable

This function is available only for the Detail aggregation property. It specifies that the aggregate attribute is ignored. For example, the calculation is applied after the data is aggregated.

This function differs from the Calculated function, which applies aggregation to the rows and then performs the calculation.

For example, for the average ( [Quantity] ) + 5 expression, when the Detail aggregation property is set to Not Applicable, five is added to the average of the single Quantity value. When the function is set to Calculated, five is added to the average of a set of numbers.

This setting should not be applied to a simple model reference.

This setting is relevant only for reports that are upgraded from IBM Cognos ReportNet 1.x.

Standard deviation

Returns the standard deviation of the selected data item.

Summarize

Aggregates data based on model or data type information. This function can be thought of as a calculate and then aggregate rule. Data is aggregated using the following rules:

If the underlying data source type is relational and the data item or calculation is a reference to a single fact query item in the model that has the Regular Aggregate property set to Sum, Maximum, Minimum, Average, or Count, aggregate data using this function. Otherwise, data is aggregated according to the data type of the data item as follows:

• Total is applied for numeric and interval values
• Maximum is applied for date, time, and date-time values
• Count is applied for everything else

The underlying data source type can be dimensional and the data item or calculation a reference to a single item in the model. In this case, if the Regular Aggregate property of the model item is not unknown, the summary function that corresponds to the Regular Aggregate property is applied. If the Regular Aggregate property is unknown, set the function to Calculated.

For example, a list contains the data item Quantity with the Detail aggregation property set to Average. You add a query calculation named Quantity Summarize. You define its expression as Quantity + 100 and you set its Detail aggregation property to Summarize. When you run the report, the values for Quantity Summarize are computed by first adding 100 to each value for Quantity and then calculating the total. The total is calculated because Quantity contains numeric values and the expression for Quantity Summarize is not a simple data item reference. If Quantity Summarize is defined as Quantity, the function Average is applied to each value.

Total

Adds all existing values.

Variance

Returns the variance of the selected data item.