gustavodemorais commented on code in PR #26113:
URL: https://github.com/apache/flink/pull/26113#discussion_r1955988937
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docs/content/docs/dev/table/sql/queries/joins.md:
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@@ -326,16 +326,55 @@ FROM Orders AS o
In the example above, the Orders table is enriched with data from the
Customers table which resides in a MySQL database. The `FOR SYSTEM_TIME AS OF`
clause with the subsequent processing time attribute ensures that each row of
the `Orders` table is joined with those Customers rows that match the join
predicate at the point in time when the `Orders` row is processed by the join
operator. It also prevents that the join result is updated when a joined
`Customer` row is updated in the future. The lookup join also requires a
mandatory equality join predicate, in the example above `o.customer_id = c.id`.
-Array Expansion
+Array, Multiset and Map Expansion
--------------
-Returns a new row for each element in the given array. Unnesting `WITH
ORDINALITY` is not yet supported.
+Unnest returns a new row for each element in the given array, multiset or map.
Supports both `CROSS JOIN` and `LEFT JOIN`.
+```sql
+-- Returns a new row for each element in a constant array
+SELECT * FROM (VALUES('order_1')), UNNEST(ARRAY["shirt", "pants", "hat"])
+
+id product_name
+======= ============
+order_1 shirt
+order_1 pants
+order_1 hat
+
+-- Returns a new row for each element in the array
+-- assuming a Orders table with an array column `product_names`
+SELECT order_id, product_name
+FROM Orders
+ CROSS JOIN UNNEST(product_names) AS t(product_name)
+```
+
+Unnesting `WITH ORDINALITY` is also supported.
+
```sql
-SELECT order_id, tag
-FROM Orders CROSS JOIN UNNEST(tags) AS t (tag)
+-- Returns a new row for each element in a constant array and its position in
the array
+SELECT *
+FROM (VALUES('order_1'))
Review Comment:
> it might be easier to understand with a space after VALUES and a second
value
Extended the example with both notes
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