> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kinetica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Window Ranking Functions

<AccordionGroup>
  <Accordion title="CUME_DIST()" id="cume_dist" defaultOpen>
    The relative position of the current row within the cumulative distribution of the selected
    partition, expressed as a percentage from `0` (exclusive) to `1` (inclusive). The formula for
    this calculation is as follows:

    ```
    (count of <= records within partition) / (partition row count)
    ```

    This function is shorthand for using the `COUNT()` function in separate partition statements to
    arrive at the same result:

    ```sql theme={null}
    DOUBLE
    (
        COUNT(*) OVER
        (
            PARTITION BY <partition_column>
            ORDER BY <sort_column>
        )
    ) /
    (
        COUNT(*) OVER
        (
            PARTITION BY <partition_column>
            ORDER BY <sort_column>
            ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
        )
    )
    ```
  </Accordion>

  <Accordion title="DENSE_RANK()" id="dense_rank" defaultOpen>
    Number of the current row within the selected partition except rows with identical values
    evaluate to different ranks. Starts at 1
  </Accordion>

  <Accordion title="FIRST_VALUE(<column>) [<IGNORE | RESPECT> NULLS]" id="first_value-<column>-<ignore-|-respect>-nulls" defaultOpen>
    The value found in the first row within a frame of the given expression. Optionally, add
    `IGNORE NULLS` or `RESPECT NULLS` to the function syntax to ignore or respect `nulls`,
    respectively.
  </Accordion>

  <Accordion title="LAG(<column>[, <num>]) [<IGNORE | RESPECT> NULLS]" id="lag-<column>-<num>-<ignore-|-respect>-nulls" defaultOpen>
    The value of the row before the given expression's value. Provide an additional comma-separated
    value to specify which row to select, e.g., `LAG(vendor_id, 3)` would list the value in the
    `vendor_id` column from three rows prior to the current row. Optionally, add `IGNORE NULLS`
    or `RESPECT NULLS` to the function syntax to ignore or respect `nulls` respectively.
  </Accordion>

  <Accordion title="LAST_VALUE(<column>) [<IGNORE | RESPECT> NULLS]" id="last_value-<column>-<ignore-|-respect>-nulls" defaultOpen>
    The value found in the last row within a frame of the given expression. Optionally, add
    `IGNORE NULLS` or `RESPECT NULLS` to the function syntax to ignore or respect
    `nulls` respectively.
  </Accordion>

  <Accordion title="LEAD(<column>[, <num>]) [<IGNORE | RESPECT> NULLS]" id="lead-<column>-<num>-<ignore-|-respect>-nulls" defaultOpen>
    The value of the row after the given expression's value. Provide an additional comma-separated
    value to specify which row to select, e.g., `LEAD(vendor_id, 3)` would list the value in the
    `vendor_id` column from three rows after the current row. Optionally, add `IGNORE NULLS`
    or `RESPECT NULLS` to the function syntax to ignore or respect `nulls` respectively.
  </Accordion>

  <Accordion title="NTILE(<num of groups>)" id="ntile-<num-of-groups>" defaultOpen>
    The group number of the row after partitioning the rows into `num of groups` groups.  For
    example, `NTILE(4)` will partition data by quartiles and return the associated group number,
    `1` to `4`.
  </Accordion>

  <Accordion title="PERCENT_RANK()" id="percent_rank" defaultOpen>
    The rank of the current row within the selected partition, expressed as a percentage from `0`
    to `1`, inclusive. The formula for this calculation is as follows:

    ```
    (rank within partition - 1) / (partition row count - 1)
    ```

    This function is shorthand for using the `RANK()` & `COUNT()` functions in separate partition
    statements to arrive at the same result:

    ```sql theme={null}
    DOUBLE
    (
        RANK() OVER
        (
            PARTITION BY <partition_column>
            ORDER BY <sort_column>
        ) - 1
    ) /
    (
        COUNT(*) OVER
        (
            PARTITION BY <partition_column>
            ORDER BY <sort_column>
            ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING
        ) - 1
    )
    ```
  </Accordion>

  <Accordion title="RANK()" id="rank" defaultOpen>
    Number of the current row within the selected partition. However, rows with identical values
    evaluate to the same rank. Starts at 1
  </Accordion>

  <Accordion title="ROW_NUMBER()" id="row_number" defaultOpen>
    Number of the current row within the selected partition. Starts at 1
  </Accordion>
</AccordionGroup>