row_number aggregate window function

docs/expressions/AggregateWindowFunction.md

@@ -6,5 +6,21 @@
 
 * `NthValue`
 * `RankLike`
-* `RowNumberLike`
+* [RowNumberLike](RowNumberLike.md)
 * `SizeBasedWindowFunction`
+
+## Frame { #frame }
+
+??? note "WindowFunction"
+
+    ```scala
+    frame: WindowFrame
+    ```
+
+    `frame` is part of the [WindowFunction](WindowFunction.md#frame) abstraction.
+
+`frame` is a `SpecifiedWindowFrame` with the following:
+
+* `RowFrame` type
+* `UnboundedPreceding` lower expression
+* `CurrentRow` lower expression

docs/expressions/DeclarativeAggregate.md

@@ -10,14 +10,18 @@ title: DeclarativeAggregate
 
 ## Contract
 
-### <span id="evaluateExpression"> evaluateExpression
+### Evaluating Expression { #evaluateExpression }
 
 ```scala
 evaluateExpression: Expression
 ```
 
 Catalyst [Expression](Expression.md) to calculate the final value of this aggregate function
 
+See:
+
+* [RowNumber](RowNumber.md#evaluateExpression)
+
 Used when:
 
 * `EliminateAggregateFilter` logical optimization is executed
@@ -73,6 +77,7 @@ Catalyst [Expression](Expression.md)s to update the mutable aggregation buffer b
 See:
 
 * [Count](Count.md#updateExpressions)
+* [RowNumber](RowNumber.md#updateExpressions)
 * [SimpleTypedAggregateExpression](SimpleTypedAggregateExpression.md#updateExpressions)
 
 Used when:

docs/expressions/RowNumber.md

@@ -0,0 +1,35 @@
+---
+title: RowNumber
+---
+
+# RowNumber Aggregate Window Leaf Expression
+
+`RowNumber` is a [RowNumberLike](RowNumberLike.md) leaf expression known as [row_number](#prettyName).
+
+## Evaluating Expression { #evaluateExpression }
+
+??? note "DeclarativeAggregate"
+
+    ```scala
+    evaluateExpression: AttributeReference
+    ```
+
+    `evaluateExpression` is part of the [DeclarativeAggregate](DeclarativeAggregate.md#evaluateExpression) abstraction.
+
+`evaluateExpression` is the [rowNumber](RowNumberLike.md#rowNumber) attribute reference.
+
+## Pretty Name { #prettyName }
+
+??? note "Expression"
+
+    ```scala
+    prettyName
+    ```
+
+    `prettyName` is part of the [Expression](Expression.md#prettyName) abstraction.
+
+`prettyName` is the following text:
+
+```text
+row_number
+```

docs/expressions/RowNumberLike.md

@@ -0,0 +1,49 @@
+---
+title: RowNumberLike
+---
+
+# RowNumberLike Aggregate Window Function Expressions
+
+`RowNumberLike` is an extension of the [AggregateWindowFunction](AggregateWindowFunction.md) abstraction for [aggregate window function leaf expressions](#implementations).
+
+## Implementations
+
+* `CumeDist`
+* `NTile`
+* [RowNumber](RowNumber.md)
+
+## rowNumber Attribute Reference { #rowNumber }
+
+```scala
+rowNumber: AttributeReference
+```
+
+`rowNumber` is an `AttributeReference` with the following properties:
+
+* `rowNumber` name
+* `IntegerType` data type
+* [nullable](Expression.md#nullable) disabled (`false`)
+
+## Aggregation Buffer Attributes { #aggBufferAttributes }
+
+??? note "AggregateFunction"
+
+    ```scala
+    aggBufferAttributes: Seq[AttributeReference]
+    ```
+
+    `aggBufferAttributes` is part of the [AggregateFunction](AggregateFunction.md#aggBufferAttributes) abstraction.
+
+`aggBufferAttributes` is a collection with the [rowNumber](#rowNumber) attribute reference.
+
+## Update Expressions { #updateExpressions }
+
+??? note "DeclarativeAggregate"
+
+    ```scala
+    updateExpressions: Seq[Expression]
+    ```
+
+    `updateExpressions` is part of the [DeclarativeAggregate](DeclarativeAggregate.md#updateExpressions) abstraction.
+
+`updateExpressions` is a collection with the [rowNumber](#rowNumber) attribute reference incremented (by 1).

docs/expressions/WindowFunction.md

@@ -23,13 +23,19 @@
 1. `ResolveWindowOrder`
 1. [ExtractWindowExpressions](../logical-analysis-rules/ExtractWindowExpressions.md)
 
-## <span id="frame"> WindowFrame
+## WindowFrame { #frame }
 
 ```scala
 frame: WindowFrame
 ```
 
-`frame` is `UnspecifiedFrame` by default.
+`frame` is an `UnspecifiedFrame` by default.
+
+See:
+
+* [AggregateWindowFunction](AggregateWindowFunction.md#frame)
+
+---
 
 `frame` is used when:
 

docs/standard-functions/windows-functions.md

@@ -2,19 +2,64 @@
 title: Window
 ---
 
-# Standard Functions for Window Aggregation (Window Functions)
+# Aggregate Window Functions
 
-**Window aggregate functions** (aka **window functions** or **windowed aggregates**) are functions that perform a calculation over a group of records called **window** that are in _some_ relation to the current record (i.e. can be in the same partition or frame as the current row).
+**Aggregate Window Functions** (aka **window functions** or **windowed aggregates**) are functions that perform a calculation over a group of records called **window** that are in _some_ relation to the current record (i.e. can be in the same partition or frame as the current row).
 
 In other words, when executed, a window function computes a value for each and every row in a window (per [window specification](../window-functions/WindowSpec.md)).
 
 Window functions are also called **over functions** due to how they are applied using [over](../Column.md#over) operator.
 
 Spark SQL supports three kinds of window functions:
 
-* _ranking_ functions
-* _analytic_ functions
-* _aggregate_ functions
+* [Aggregate functions](aggregate-functions.md)
+* Analytic functions
+* [Ranking functions](#ranking-functions)
+
+## Ranking Functions
+
+### row_number { #row_number }
+
+```scala
+row_number(): Column
+```
+
+`row_number` assigns a unique, sequential number to each row within a window partition according to the ordering of rows (starting from 1).
+
+Internally, `row_number` creates a [RowNumber](../expressions/RowNumber.md) aggregate window leaf expression.
+
+```text
+val buckets = spark.range(5).withColumn("bucket", 'id % 3)
+// Make duplicates
+val input = buckets.union(buckets)
+```
+
+```scala
+import org.apache.spark.sql.expressions.Window
+val windowSpec = Window.partitionBy('bucket).orderBy('id)
+```
+
+```scala
+val q = input.withColumn("row_number", row_number() over windowSpec)
+```
+
+```text
+scala> q.show
++---+------+----------+
+| id|bucket|row_number|
++---+------+----------+
+|  0|     0|         1|
+|  0|     0|         2|
+|  3|     0|         3|
+|  3|     0|         4|
+|  1|     1|         1|
+|  1|     1|         2|
+|  4|     1|         3|
+|  4|     1|         4|
+|  2|     2|         1|
+|  2|     2|         2|
++---+------+----------+
+```
 
 <!---
 ## Review Me
@@ -40,9 +85,6 @@ Spark SQL supports three kinds of window functions:
 | <<ntile, ntile>>
 |
 
-| <<row_number, row_number>>
-|
-
 .3+^.^| *Analytic functions*
 
 | <<cume_dist, cume_dist>>
@@ -718,48 +760,6 @@ scala> dataset.withColumn("cume_dist", cume_dist over windowSpec).show
 +---+------+------------------+
 ----
 
-=== [[row_number]] Sequential numbering per window partition -- `row_number` Window Function
-
-[source, scala]
-----
-row_number(): Column
-----
-
-`row_number` returns a sequential number starting at `1` within a window partition.
-
-[source, scala]
-----
-val buckets = spark.range(9).withColumn("bucket", 'id % 3)
-// Make duplicates
-val dataset = buckets.union(buckets)
-
-import org.apache.spark.sql.expressions.Window
-val windowSpec = Window.partitionBy('bucket).orderBy('id)
-scala> dataset.withColumn("row_number", row_number() over windowSpec).show
-+---+------+----------+
-| id|bucket|row_number|
-+---+------+----------+
-|  0|     0|         1|
-|  0|     0|         2|
-|  3|     0|         3|
-|  3|     0|         4|
-|  6|     0|         5|
-|  6|     0|         6|
-|  1|     1|         1|
-|  1|     1|         2|
-|  4|     1|         3|
-|  4|     1|         4|
-|  7|     1|         5|
-|  7|     1|         6|
-|  2|     2|         1|
-|  2|     2|         2|
-|  5|     2|         3|
-|  5|     2|         4|
-|  8|     2|         5|
-|  8|     2|         6|
-+---+------+----------+
-----
-
 === [[ntile]] `ntile` Window Function
 
 [source, scala]

mkdocs.yml

@@ -324,6 +324,8 @@ nav:
       - Predicate: expressions/Predicate.md
       - Projection: expressions/Projection.md
       - expressions/PythonUDF.md
+      - RowNumber: expressions/RowNumber.md
+      - RowNumberLike: expressions/RowNumberLike.md
       - RowOrdering: expressions/RowOrdering.md
       - RuntimeReplaceable: expressions/RuntimeReplaceable.md
       - ScalaAggregator: expressions/ScalaAggregator.md