gengliangwang opened a new pull request, #37541:
URL: https://github.com/apache/spark/pull/37541
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### What changes were proposed in this pull request?
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Introduce a new SQL function `get()`: Returns element of array at given
(0-based) index. If the index points
outside of the array boundaries, then this function returns NULL.
Examples:
```
> SELECT _FUNC_(array(1, 2, 3), 2);
2
> SELECT _FUNC_(array(1, 2, 3), 3);
NULL
> SELECT _FUNC_(array(1, 2, 3), -1);
NULL
```
### Why are the changes needed?
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Currently, when accessing array element with invalid index under ANSI SQL
mode, the error is like:
```
[INVALID_ARRAY_INDEX] The index -1 is out of bounds. The array has 3
elements. Use `try_element_at` and increase the array index by 1(the starting
array index is 1 for `try_element_at`) to tolerate accessing element at invalid
index and return NULL instead. If necessary set "spark.sql.ansi.enabled" to
"false" to bypass this error.
```
The provided solution is complicated. I suggest introducing a new method
`get()` which always returns null on an invalid array index. This is from
https://docs.snowflake.com/en/sql-reference/functions/get.html.
Note: since Spark's map access always returns null, let's don't support map
type in the get method for now.
### Does this PR introduce _any_ user-facing change?
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Yes, a new SQL function `get()`: returns element of array at given (0-based)
index. If the index points
outside of the array boundaries, then this function returns NULL.
### How was this patch tested?
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New UT
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