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Docs: Add unnest to SQL Reference #10839

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merged 5 commits into from
Jun 11, 2024
Merged

Docs: Add unnest to SQL Reference #10839

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22be392
Add unnest to SQL Reference
gloomweaver Jun 9, 2024
d6268b6
Add unnest docs for struct, add additional example for unnest array
gloomweaver Jun 11, 2024
8a7d1d5
unnest -> unnest (struct)
gloomweaver Jun 11, 2024
0735c3d
Merge remote-tracking branch 'apache/main' into add-unnest-to-sql-ref…
alamb Jun 11, 2024
28342b3
prettier
alamb Jun 11, 2024
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25 changes: 25 additions & 0 deletions docs/source/user-guide/sql/scalar_functions.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2085,6 +2085,7 @@ to_unixtime(expression[, ..., format_n])
- [string_to_array](#string_to_array)
- [string_to_list](#string_to_list)
- [trim_array](#trim_array)
- [unnest](#unnest)
- [range](#range)

### `array_append`
Expand Down Expand Up @@ -3346,6 +3347,30 @@ trim_array(array, n)
Can be a constant, column, or function, and any combination of array operators.
- **n**: Element to trim the array.

### `unnest`

Transforms an array into rows.

#### Arguments

- **array**: Array expression to unnest.
Can be a constant, column, or function, and any combination of array operators.

#### Example

```
> select unnest(make_array(1, 2, 3, 4, 5));
+------------------------------------------------------------------+
| unnest(make_array(Int64(1),Int64(2),Int64(3),Int64(4),Int64(5))) |
+------------------------------------------------------------------+
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
+------------------------------------------------------------------+
```

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unnest also works for structs. Can you possibly add this example too?

> create table foo as values (named_struct('a', 5, 'b', 'a string'));
0 row(s) fetched.
Elapsed 0.008 seconds.

> select * from foo;
+---------------------+
| column1             |
+---------------------+
| {a: 5, b: a string} |
+---------------------+
1 row(s) fetched.
Elapsed 0.003 seconds.

> select unnest(column1) from foo;
+-----------------------+-----------------------+
| unnest(foo.column1).a | unnest(foo.column1).b |
+-----------------------+-----------------------+
| 5                     | a string              |
+-----------------------+-----------------------+
1 row(s) fetched.
Elapsed 0.003 seconds.

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We could merge this PR as is, as well

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Yeah, sure. This should be in Struct Functions right?

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I would also love to add a range example

select unnest(range(0, 100000))

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@alamb alamb Jun 11, 2024 •
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Yeah, sure. This should be in Struct Functions right?

I think that would make sense.

FWIW here is an example:

DataFusion CLI v39.0.0
> select unnest(range(0, 10));
+-----------------------------------+
| unnest(range(Int64(0),Int64(10))) |
+-----------------------------------+
| 0                                 |
| 1                                 |
| 2                                 |
| 3                                 |
| 4                                 |
| 5                                 |
| 6                                 |
| 7                                 |
| 8                                 |
| 9                                 |
+-----------------------------------+
10 row(s) fetched.
Elapsed 0.054 seconds.

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Added docs for struct unnest and example this range for array.
Couldn't link to it because of the name.
Is there a way to assign custom id to a block with sphinx? Tried labels, didn't work, so named it unnest (struct).

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Is there a way to assign custom id to a block with sphinx? Tried labels, didn't work, so named it unnest (struct).

I am not sure to be honest

### `range`

Returns an Arrow array between start and stop with step. `SELECT range(2, 10, 3) -> [2, 5, 8]` or `SELECT range(DATE '1992-09-01', DATE '1993-03-01', INTERVAL '1' MONTH);`
Expand Down