gustavodemorais opened a new pull request, #26113:
URL: https://github.com/apache/flink/pull/26113
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## What is the purpose of the change
The SQL standard specifies a WITH ORDINALITY clause that can be appended to
any UNNEST function call, which returns a new row for each element and its
position in the data structure being unnested.
Examples:
```sql
– Returns a new row for each element in a constant array and its position in
the array
SELECT *
FROM (VALUES('order_1'))
CROSS JOIN UNNEST(ARRAY["shirt", "pants", "hat"])
WITH ORDINALITY AS t(product_name, index)
id product_name index
======= ============ =====
order_1 shirt 1
order_1 pants 2
order_1 hat 3
– Returns a new row for each element and its position in the array assuming
a Orders table with an array column `product_names`
SELECT order_id, product_name, product_index
FROM Orders
CROSS JOIN UNNEST(product_names)
WITH ORDINALITY AS t(product_name, product_index)
```
A unnest with ordinality will return each element and the position of the
element in the data structure, 1-indexed. The order of the elements for arrays
and multisets is guaranteed. Since maps are unordered, the order of the
elements is not guaranteed.
## Brief change log
- Update unnest rule and unnest row functions to support unnest with and
without ordinality
- Revamp outdated unnest documentation
## Verifying this change
This change added tests and can be verified as follows:
- Added stream tests
- Added batch tests
- Added plan tests
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): no
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: no
- The serializers: no
- The runtime per-record code paths (performance sensitive): no
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
- The S3 file system connector: no
## Documentation
- Does this pull request introduce a new feature? yes
- If yes, how is the feature documented? docs
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