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Eric Xiao edited comment on FLINK-20578 at 10/26/22 6:43 PM: ------------------------------------------------------------- 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 in other query engines and these are the results I got: Trino: !Screen Shot 2022-10-26 at 2.28.49 PM.png|width=957,height=340! They use unknown datatype Spark: !image-2022-10-26-14-42-08-468.png|width=505,height=112! They use unknown datatype BigQuery: !Screen Shot 2022-10-25 at 10.50.47 PM.png|width=374,height=158! !image-2022-10-26-14-42-57-579.png|width=373,height=125! They use integer datatype 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? 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 in other query engines and these are the results I got: Trino: !Screen Shot 2022-10-26 at 2.28.49 PM.png|width=957,height=340! They use unknown datatype BigQuery: !Screen Shot 2022-10-25 at 10.50.47 PM.png|width=374,height=158!!Screen Shot 2022-10-25 at 10.50.42 PM.png|width=761,height=148! They use integer datatype > 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, > Screen Shot 2022-10-26 at 2.28.49 PM.png, image-2022-10-26-14-42-08-468.png, > image-2022-10-26-14-42-57-579.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? -- This message was sent by Atlassian Jira (v8.20.10#820010)