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https://issues.apache.org/jira/browse/IMPALA-9499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17073614#comment-17073614
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Gabor Kaszab commented on IMPALA-9499:
--------------------------------------
I found this in one of the old design docs for complex types:
"We will not perform automatic serialization of complex types to protect users
against inadvertently writing a query that is very expensive due to excessive
serialization. Users must explicitly wrap complex column references in the
top-level select list with a serialization function such as ToJson(). For
example, the following queries are illegal:
SELECT orders FROM customers
SELECT * FROM customers"
I tend to agree with the select * part. We might want to leave the logic as it
is and omit the complex types for a select *. Other solution is to somehow
signal to the user that there was something we omited so you don't see the
whole table. Or we can fill the complex typed columns with some dummy string
value.
> Display support for all complex types in a SELECT * query
> ---------------------------------------------------------
>
> Key: IMPALA-9499
> URL: https://issues.apache.org/jira/browse/IMPALA-9499
> Project: IMPALA
> Issue Type: New Feature
> Reporter: Gabor Kaszab
> Assignee: Adam Tamas
> Priority: Major
> Labels: complextype
>
> Covers all complex types (Struct, Array, Map) for both Parquet and ORC file
> formats.
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