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https://issues.apache.org/jira/browse/FLINK-32260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17738140#comment-17738140
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Hanyu Zheng commented on FLINK-32260:
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I am currently attempting to adjust an array slice function to switch from a
0-based index to a 1-based index . However, I have encountered some issues
related to this change, specifically with regards to handling the start_offset
and end_offset:
In the context of a 1-based index, if we have a query like array_slice[0, 2],
what would be the expected output? Since 0 is not a valid index in a 1-based
system, how should we handle this start_offset or end_offset when it is set to
0?
If we have a query like array_slice[1, 0], how should this be interpreted?
According to the Google Cloud array_slice definition, the function should
return an empty array if the position of the start_offset in the array is after
the position of the end_offset. But in this case, since we are using a 1-based
index, should we consider these positions to be the same and return [1], or
should we consider end_offset of 0 to be invalid and return an empty array?
[~Sergey Nuyanzin] [~twalthr]
> Add ARRAY_SLICE support in SQL & Table API
> ------------------------------------------
>
> Key: FLINK-32260
> URL: https://issues.apache.org/jira/browse/FLINK-32260
> Project: Flink
> Issue Type: Improvement
> Components: Table SQL / Planner
> Affects Versions: 1.18.0
> Reporter: Bonnie Varghese
> Assignee: Hanyu Zheng
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.18.0
>
>
> Implement the {{array_slice}} function to extract a subset of elements from
> an array.
> Description: The {{array_slice}} function in the ETL pipeline allows you to
> extract a subset of elements from an array based on the specified starting
> index and length. It supports both positive and negative indices, where
> positive indices start from 1 (the first element) and negative indices start
> from the end of the array (-1 being the last element).
> Syntax:
>
> code
> {code:java}
> array_slice[x: array, start: int, length: int] -> array{code}
> {{ }}
> Arguments:
> * {{{}x{}}}: The input array from which to extract the subset of elements.
> * {{{}start{}}}: The starting index of the subset. If positive, it
> represents the index from the beginning of the array. If negative, it
> represents the index from the end of the array (-1 being the last element).
> * {{{}length{}}}: The length of the subset to be extracted.
> Returns: An array containing the subset of elements extracted from the input
> array {{{}x{}}}. The subset starts from the specified {{start}} index and has
> the specified {{{}length{}}}.
> Examples:
> # Extracting a subset from an array starting from index 2 with length 2:
>
> {code:java}
> array_slice[array[1, 2, 3, 4], 2, 2] Output: [2, 3]{code}
> 2. Extracting a subset from an array starting from the second-to-last
> element with length
>
> {code:java}
> array_slice[array[1, 2, 3, 4], -2, 2]
> Output: [3, 4]{code}
> see also:
> spark:[https://spark.apache.org/docs/latest/api/sql/index.html#slice]
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