Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/3806#discussion_r116146470
--- Diff: docs/dev/table_api.md ---
@@ -1099,14 +1099,14 @@ Temporal intervals can be represented as number of
months (`Types.INTERVAL_MONTH
The Table API is a declarative API to define queries on batch and
streaming tables. Projection, selection, and union operations can be applied
both on streaming and batch tables without additional semantics. Aggregations
on (possibly) infinite streaming tables, however, can only be computed on
finite groups of records. Window aggregates group rows into finite groups based
on time or row-count intervals and evaluate aggregation functions once per
group. For batch tables, windows are a convenient shortcut to group records by
time intervals.
-Windows are defined using the `window(w: Window)` clause and require an
alias, which is specified using the `as` clause. In order to group a table by a
window, the window alias must be referenced in the `groupBy(...)` clause like a
regular grouping attribute.
+Windows are defined using the `window(w: Window)` clause and the window
must have an alias. In order to group a table by a window, the window alias
must be referenced in the `groupBy(...)` clause like a regular grouping
attribute.
The following example shows how to define a window aggregation on a table.
<div class="codetabs" markdown="1">
<div data-lang="java" markdown="1">
{% highlight java %}
Table table = input
- .window([Window w].as("w")) // define window with alias w
+ .window([WindowWithoutAlias w].as("w")) // define window with alias w
--- End diff --
Yes, But the `as` method does not belong to `Window`. I think the user may
has a little bit confused.
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