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https://issues.apache.org/jira/browse/FLINK-20578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17624154#comment-17624154
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Eric Xiao edited comment on FLINK-20578 at 10/26/22 4:19 AM:
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Hi I wanted to get more involved in contributing to the Flink project and found
this starter task - my team is working with the Table / SQL APIs, so I thought
this would be a good beginning task to work on :). [~surahman] are you still
working on this issue? If not I would love to take over.
> If Flink support empty array, which data type of elements in array should be
> ? Does it cause new problems.
[~pensz] I think there are two paths:
1. If we given more context on what the array type should be we should try
using that.
2. If we have no context we use a default data type.
Path #1 -
I can forsee queries as such `SELECT COALESCE(empty_str_column,ARRAY[])` where
we could infer the data should be of string type and try to return that.
Path #2 - Default Data Type
I believe the query in the issue would qualify as a query with no context. I
tested a similar query in Trino (Presto) and BigQuery and they use a data type
Integer as the data type. This could be a good default behaviour?
!Screen Shot 2022-10-25 at 10.50.42 PM.png!
!Screen Shot 2022-10-25 at 10.50.47 PM.png!
!Screen Shot 2022-10-25 at 11.01.06 PM.png!
was (Author: JIRAUSER295489):
Hi I wanted to get more involved in contributing to the Flink project and found
this starter task - my team is working with the Table / SQL APIs, so I thought
this would be a good beginning task to work on :). [~surahman] are you still
working on this issue, I noticed it has been a year since your last comment.
> If Flink support empty array, which data type of elements in array should be
> ? Does it cause new problems.
[~pensz] I think there are two paths:
1. If we given more context on what the array type should be we should try
using that.
2. If we have no context we use a default data type.
Path #1 -
I can forsee queries as such `SELECT COALESCE(empty_str_column,ARRAY[])` where
we could infer the data should be of string type and try to return that.
Path #2 - Default Data Type
I believe the query in the issue would qualify as a query with no context. I
tested a similar query in Trino (Presto) and BigQuery and they use a data type
Integer as the data type. This could be a good default behaviour?
!Screen Shot 2022-10-25 at 10.50.42 PM.png!
!Screen Shot 2022-10-25 at 10.50.47 PM.png!
!Screen Shot 2022-10-25 at 11.01.06 PM.png!
> Cannot create empty array using ARRAY[]
> ---------------------------------------
>
> Key: FLINK-20578
> URL: https://issues.apache.org/jira/browse/FLINK-20578
> Project: Flink
> Issue Type: Sub-task
> Components: Table SQL / API
> Affects Versions: 1.11.2
> Reporter: Fabian Hueske
> Priority: Major
> Labels: pull-request-available, starter
> Fix For: 1.17.0
>
> Attachments: Screen Shot 2022-10-25 at 10.50.42 PM.png, Screen Shot
> 2022-10-25 at 10.50.47 PM.png, Screen Shot 2022-10-25 at 11.01.06 PM.png
>
>
> Calling the ARRAY function without an element (`ARRAY[]`) results in an error
> message.
> Is that the expected behavior?
> How can users create empty arrays?
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