Window functions

Window functions in DataLens are calculated as aggregate functions of measures. At the same time, grouping by dimensions differs from the grouping set in the chart. Grouping parameters are specified in the function call as a list of dimensions to be included in the grouping (WITHIN ...) or excluded from it (AMONG ...).

Given that measures are aggregated values, one may consider window functions in DataLens as aggregations of aggregations. One should note that not all aggregate functions would have the result of aggregating particular results that is identical to the general aggregation of values.

For example, when calculating the sum of a measure for each group and then adding these values together, you will get the total sum of the measure in all groups:

SUM(SUM(a) UNION SUM(b)) = SUM(a UNION b)

When counting the amount of measure values for each group and then trying to calculate the amount from the sum of these values, you will get the amount of amounts (summands in the sum) rather than the total amount of values in all groups:

COUNT(COUNT(a) UNION COUNT(b)) = 2

Example

Where:

• Sales: Sum of the sales measure in the categories
• Order Count: Amount of the order measure values in the categories
• Sales_Furniture+Technology: Total sum of the sales measure in all categories:

  SUM_IF([Sales], [Category] = 'Furniture' TOTAL) + SUM_IF([Sales], [Category] = 'Technology' TOTAL)
  

• OrderCount_Furniture+Technology: Amount of amounts of the order measure values:

  COUNT(COUNT_IF([Order Count], [Category] = 'Furniture' TOTAL) +  COUNT_IF([Order Count], [Category] = 'Technology' TOTAL) TOTAL)
  

Usage RestrictionsUsage Restrictions

1. The first argument in window functions can only be measures.

   For the AVG_IF, COUNT_IF, SUM_IF window functions, the first argument (expression in the function description) must always be a measure.

   Example:

   AVG_IF([Profit], [Profit] > 5)

   For other window functions, the first (and only) argument (value in the function description) must always be a measure, too.

   Examples:

   • Correct formula: SUM(SUM([Profit]) TOTAL).
   • Incorrect formula: RANK([Profit] TOTAL), where [Profit] is a non-aggregated expression.

2. For grouping window functions, only the dimensions used to build the chart can be applied. Only the dimensions used to build the chart set the grouping when calculating a measure. These dimensions define how values are split into groups and therefore have fixed values in each group.

   If you specify a dimension that was not used to build the chart, it won't have a fixed value and the value can be different in each group row. As a result, it will be impossible to determine which value of this dimension must be used to calculate the measure. This limitation applies to the WITHIN and AMONG grouping types.

   Examples:

   • Correct formula: RANK(SUM([Profit]) WITHIN [Category]) in the chart with grouping by the [Order Date] and [Category] dimensions. [Category] is used when building the chart.
   • Correct formula: RANK(SUM([Profit]) WITHIN [Category]) in the chart with grouping by the [Order Date] and [City] dimensions. [Category] is not part of the grouping, so it will not be used in the calculation. The result will be the same as when using the RANK(SUM([Profit]) TOTAL) formula.
   • Incorrect formula: RANK(SUM([Profit]) AMONG [City]) in the chart with grouping by the [Order Date] and [Category] dimensions. Running the function will return the Unknown dimension for window error.

3. Window functions do not support managing the level of detail. This is only available for aggregate functions.

4. For functions that depend on sorting order, the fields listed in ORDER BY must be used when building the chart.

5. If a window function is used to build a Table chart, we don't recommend enabling the display of Total in the settings. This may cause an error.

SyntaxSyntax

The general syntax for window functions is as follows:

<WINDOW_FUNCTION_NAME>(
    arg1, arg2, ...

    [ TOTAL
    | WITHIN dim1, dim2, ...
    | AMONG dim1, dim2, ... ]

    [ ORDER BY field1, field2, ... ]

    [ BEFORE FILTER BY filtered_field1, ... ]
)

It starts off, just like a regular function call, with its name and arguments (arg1, arg2, ... in this case).

GroupingGrouping

The arguments are followed by a window grouping, which can be one of three types:

• TOTAL (equivalent to WITHIN without dimensions): all query entries fall into a single window.
• WITHIN dim1, dim2, ... : records are grouped by the dimensions dim1, dim2, ....
• AMONG dim1, dim2, ... : records are grouped by all dimensions from the query, except those listed. For example, if we use formula RSUM(SUM([Sales]) AMONG dim1, dim2) with dimensions dim1, dim2, dim3, dim4 in the data query, then the entries will be grouped by dim3 and dim4, so it will be equivalent to RSUM([Sales] WITHIN dim3, dim4).

The grouping clause is optional. TOTAL is used by default.

OrderingOrdering

After the grouping comes the ordering clause. It is only supported for order-dependent functions:

The ordering clause is optional for these functions.

See the descriptions of these functions for more information on how this order affects the result value.
The ORDER BY clause accepts dimensions as well as measures. It also supports the standard ASC/DESC syntax (ASC is assumed by default) to specify ascending or descending order respectively:
... ORDER BY [Date] ASC, SUM([Sales]) DESC, [Category] ...

Fields listed in ORDER BY are combined with fields listed in the chart's sorting section.
Example:

• Function — ... ORDER BY [Date] DESC, [City].
• Chart — Sorted by Date and Category.
• Result — Date (descending), City, Category.

BEFORE FILTER BYBEFORE FILTER BY

If any fields are listed in BEFORE FILTER BY, then this window function is calculated before data is filtered using these fields.

BEFORE FILTER BY applies to all nested window functions too.
Example:

• Formula — MAVG(RSUM([Sales]), 10 BEFORE FILTER BY [Date]).
• Equivalent — MAVG(RSUM([Sales] BEFORE FILTER BY [Date]), 10 BEFORE FILTER BY [Date]).

Do not use conflicting BEFORE FILTER BY clauses:

• Correct formula: MAVG(RSUM([Sales] BEFORE FILTER BY [Date], [Category]), 10 BEFORE FILTER BY [Date]) — functions are nested and ([Date]) is a subset of ([Date], [Category]).
• Correct formula: MAVG(RSUM([Sales] BEFORE FILTER BY [Category]), 10 BEFORE FILTER BY [Date]) — functions are nested, so field lists are combined in the second of the two functions.
• Correct formula: RSUM([Sales] BEFORE FILTER BY [Date], [Category]) - RSUM([Sales] BEFORE FILTER BY [Date]) — ([Date]) is a subset of ([Date], [Category]).
• Incorrect formula: RSUM([Sales] BEFORE FILTER BY [Category]) - RSUM([Sales] BEFORE FILTER BY [Date]) — functions are not nested and neither of ([Category]) and ([Date]) is a subset of the other.

Aggregate Functions as Window FunctionsAggregate Functions as Window Functions

The following aggregations can also be used as window functions:

To use the window version of the aggregate functions, you must explicitly specify the grouping (unlike other window functions, where it is optional).

For example, the SUM([Sales]) / SUM(SUM([Sales]) TOTAL) expression can be used to calculate the ratio of a group's sum of [Sales] to the sum of [Sales] among all entries.

AVGAVG

Syntax:
AVG( value TOTAL | WITHIN ... | AMONG ... )
or
AVG( value TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the average of all values. Applicable to numeric data types.

AVG_IFAVG_IF

Syntax:
AVG_IF( expression, condition TOTAL | WITHIN ... | AMONG ... )
or
AVG_IF( expression, condition TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the average of all values that meet the condition condition. If the values don't exist, it returns NULL. Applicable to numeric data types only.

COUNTCOUNT

Syntax:
COUNT( [ value ] TOTAL | WITHIN ... | AMONG ... )
or
COUNT( [ value ] TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the number of items in the specified window.

COUNT_IFCOUNT_IF

Syntax:
COUNT_IF( expression, condition TOTAL | WITHIN ... | AMONG ... )
or
COUNT_IF( expression, condition TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the number of items in the specified window meeting the expression condition.

FIRSTFIRST

Syntax:
FIRST( value )
or
FIRST( value [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the value of value from the first row in the window. See also LAST.

LAGLAG

Syntax:
LAG( value [ , offset [ , default ] ] )
or
LAG( value [ , offset [ , default ] ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns value re-evaluated against the row that is offset from the current row by offset within the specified window:

• Positive offset seeks among preceding rows.
• Negative offset seeks among following rows.

By default offset is 1.

If there is no available value (offset reaches before the first row or after the last one), then default is returned. If default is not specified, then NULL is used.

See also AGO for a non-window function alternative.

LASTLAST

Syntax:
LAST( value )
or
LAST( value [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the value of value from the last row in the window. See also FIRST.

MAVGMAVG

Syntax:
MAVG( value, rows_1 [ , rows_2 ] )
or
MAVG( value, rows_1 [ , rows_2 ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the moving average of values in a fixed-size window defined by the sort order and arguments:

Window functions with a similar behavior: MSUM, MCOUNT, MMIN, MMAX.

See also AVG, RAVG.

MAXMAX

Syntax:
MAX( value TOTAL | WITHIN ... | AMONG ... )
or
MAX( value TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the maximum value.

If value:

• number — Returns the largest number.
• date — Returns the latest date.
• string — Returns the last value in the alphabetic order.

MCOUNTMCOUNT

Syntax:
MCOUNT( value, rows_1 [ , rows_2 ] )
or
MCOUNT( value, rows_1 [ , rows_2 ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the moving count of (non-NULL) values in a fixed-size window defined by the sort order and arguments:

Window functions with a similar behavior: MSUM, MMIN, MMAX, MAVG.

See also COUNT, RCOUNT.

MINMIN

Syntax:
MIN( value TOTAL | WITHIN ... | AMONG ... )
or
MIN( value TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the minimum value.

If value:

• number — Returns the smallest number.
• date — Returns the earliest date.
• string — Returns the first value in the alphabetic order.

MMAXMMAX

Syntax:
MMAX( value, rows_1 [ , rows_2 ] )
or
MMAX( value, rows_1 [ , rows_2 ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the moving maximum of values in a fixed-size window defined by the sort order and arguments:

Window functions with a similar behavior: MSUM, MCOUNT, MMIN, MAVG.

See also MAX, RMAX.

MMINMMIN

Syntax:
MMIN( value, rows_1 [ , rows_2 ] )
or
MMIN( value, rows_1 [ , rows_2 ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the moving minimum of values in a fixed-size window defined by the sort order and arguments:

Window functions with a similar behavior: MSUM, MCOUNT, MMAX, MAVG.

See also MIN, RMIN.

MSUMMSUM

Syntax:
MSUM( value, rows_1 [ , rows_2 ] )
or
MSUM( value, rows_1 [ , rows_2 ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the moving sum of values in a fixed-size window defined by the sort order and arguments:

Window functions with a similar behavior: MCOUNT, MMIN, MMAX, MAVG.

See also SUM, RSUM.

RANKRANK

Syntax:
RANK( value [ , direction ] )
or
RANK( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ BEFORE FILTER BY ... ] )

Returns the rank of the current row if ordered by the given argument. Rows corresponding to the same value used for sorting have the same rank. If the first two rows both have rank of 1, then the next row (if it features a different value) will have rank 3, so, in effect, it is rank with gaps.

If direction is "desc" or omitted, then ranking is done from greatest to least, if "asc", then from least to greatest.

See also RANK_DENSE, RANK_UNIQUE, RANK_PERCENTILE.

RANK_DENSERANK_DENSE

Syntax:
RANK_DENSE( value [ , direction ] )
or
RANK_DENSE( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ BEFORE FILTER BY ... ] )

Returns the rank of the current row if ordered by the given argument. Rows corresponding to the same value used for sorting have the same rank. If the first two rows both have rank of 1, then the next row (if it features a different value) will have rank 2, (rank without gaps).

If direction is "desc" or omitted, then ranking is done from greatest to least, if "asc", then from least to greatest.

See also RANK, RANK_UNIQUE, RANK_PERCENTILE.

RANK_PERCENTILERANK_PERCENTILE

Syntax:
RANK_PERCENTILE( value [ , direction ] )
or
RANK_PERCENTILE( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ BEFORE FILTER BY ... ] )

Returns the relative rank (from 0 to 1) of the current row if ordered by the given argument. Calculated as (RANK(...) - 1) / (row count) .

If direction is "desc" or omitted, then ranking is done from greatest to least, if "asc", then from least to greatest.

See also RANK, RANK_DENSE, RANK_UNIQUE.

RANK_UNIQUERANK_UNIQUE

Syntax:
RANK_UNIQUE( value [ , direction ] )
or
RANK_UNIQUE( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ BEFORE FILTER BY ... ] )

Returns the rank of the current row if ordered by the given argument. Rows corresponding to the same value have different rank values. This means that rank values are sequential and different for all rows, always increasing by 1 for the next row.

If direction is "desc" or omitted, then ranking is done from greatest to least, if "asc", then from least to greatest.

See also RANK, RANK_DENSE, RANK_PERCENTILE.

RAVGRAVG

Syntax:
RAVG( value [ , direction ] )
or
RAVG( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the average of all values in a growing (or shrinking) window defined by the sort order and the value of direction:

By default "asc" is used.

Window functions with a similar behavior: RSUM, RCOUNT, RMIN, RMAX.

See also AVG, MAVG.

RCOUNTRCOUNT

Syntax:
RCOUNT( value [ , direction ] )
or
RCOUNT( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the count of all values in a growing (or shrinking) window defined by the sort order and the value of direction:

By default "asc" is used.

Window functions with a similar behavior: RSUM, RMIN, RMAX, RAVG.

See also COUNT, MCOUNT.

RMAXRMAX

Syntax:
RMAX( value [ , direction ] )
or
RMAX( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the maximum of all values in a growing (or shrinking) window defined by the sort order and the value of direction:

By default "asc" is used.

Window functions with a similar behavior: RSUM, RCOUNT, RMIN, RAVG.

See also MAX, MMAX.

RMINRMIN

Syntax:
RMIN( value [ , direction ] )
or
RMIN( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the minimum of all values in a growing (or shrinking) window defined by the sort order and the value of direction:

By default "asc" is used.

Window functions with a similar behavior: RSUM, RCOUNT, RMAX, RAVG.

See also MIN, MMIN.

RSUMRSUM

Syntax:
RSUM( value [ , direction ] )
or
RSUM( value [ , direction ] [ TOTAL | WITHIN ... | AMONG ... ] [ ORDER BY ... ] [ BEFORE FILTER BY ... ] )

Returns the sum of all values in a growing (or shrinking) window defined by the sort order and the value of direction:

By default "asc" is used.

Window functions with a similar behavior: RCOUNT, RMIN, RMAX, RAVG.

See also SUM, MSUM.

SUMSUM

Syntax:
SUM( value TOTAL | WITHIN ... | AMONG ... )
or
SUM( value TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the sum of all expression values. Applicable to numeric data types only.

SUM_IFSUM_IF

Syntax:
SUM_IF( expression, condition TOTAL | WITHIN ... | AMONG ... )
or
SUM_IF( expression, condition TOTAL | WITHIN ... | AMONG ... [ BEFORE FILTER BY ... ] )

Returns the sum of all the expression values that meet the condition condition. Applicable to numeric data types only.