[jira] [Commented] (FLINK-32260) Add ARRAY_SLICE support in SQL & Table API

["Sergey Nuyanzin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-32260?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17737730#comment-17737730 ] 

Sergey Nuyanzin commented on FLINK-32260:
-----------------------------------------

About indexing: it seems vendors are not in sync...
Google Spanner, Cosmos DB, Snowflake are 0-based

Clickhouse, DuckDB are 1-based

yes, in Flink {{SUBSTRING}} is 1-based
also in Flink {{OVERLAY}}, {{INSTR}} are 1-based (seems all string related functions)
Also array indexing in Flink is happening with 1-based approach

> 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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