row_number()

Returns the current row's index in a serialized row set.

The row index starts by default at 1 for the first row, and is incremented by 1 for each additional row. Optionally, the row index can start at a different value than 1. Additionally, the row index may be reset according to some provided predicate.

Syntax

row_number( [StartingIndex [, Restart]] )

Learn more about syntax conventions.

Parameters

Name	Type	Required	Description
StartingIndex	long		The value of the row index to start at or restart to. The default value is 1.
restart	bool		Indicates when the numbering is to be restarted to the StartingIndex value. The default is false.

Returns

The function returns the row index of the current row as a value of type long.

Examples

The following example returns a table with two columns, the first column (a) with numbers from 10 down to 1, and the second column (rn) with numbers from 1 up to 10:

Run the query

range a from 1 to 10 step 1
| sort by a desc
| extend rn=row_number()

The following example is similar to the above, only the second column (rn) starts at 7:

Run the query

range a from 1 to 10 step 1
| sort by a desc
| extend rn=row_number(7)

The last example shows how one can partition the data and number the rows per each partition. Here, we partition the data by Airport:

Run the query

datatable (Airport:string, Airline:string, Departures:long)
[
  "TLV", "LH", 1,
  "TLV", "LY", 100,
  "SEA", "LH", 1,
  "SEA", "BA", 2,
  "SEA", "LY", 0
]
| sort by Airport asc, Departures desc
| extend Rank=row_number(1, prev(Airport) != Airport)

Running this query produces the following result:

Airport	Airline	Departures	Rank
SEA	BA	2	1
SEA	LH	1	2
SEA	LY	0	3
TLV	LY	100	1
TLV	LH	1	2