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https://issues.apache.org/jira/browse/CALCITE-4999?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Dmitry Sysolyatin updated CALCITE-4999:
---------------------------------------
    Description: 
At the moment `array` function returns [RecordType ARRAY] if subquery is passed 
like an argument.
{code:java}
SELECT array(select 'toast.' || x from unnest(ARRAY['1','2']) x){code}
But Sql standard says:
{code:java}
6.38 <array value constructor>

Function
Specify construction of an array.

Format
<array value constructor> ::=
<array value constructor by enumeration>
| <array value constructor by query>

[...]

<array value constructor by query> ::=
ARRAY <table subquery>

Syntax Rules
[...]
3) If <array value constructor by query> is specified, then
a) The <query expression> QE simply contained in the <table subquery> shall be 
of degree 1 (one). Let ET be the declared type of the column in the result of 
<query expression>.
b) The declared type of the <array value constructor by query> is array with 
element type ET and maximum cardinality equal to the implementation-defined 
maximum cardinality IMDC for such array types.
{code}
Proposed solution is to return an array of scalars (e.g. INTEGER ARRAY) when 
the query returns 1 column, and continue to return an array of ROW when the 
query has 2 or more columns. And do the same for MULTISET.

  was:
At the moment query `array` function returns [RecordType ARRAY] if subquery is 
passed like an argument.
{code:java}
SELECT array(select 'toast.' || x from unnest(ARRAY['1','2']) x){code}

But Sql standard says:
{code:java}
6.38 <array value constructor>

Function
Specify construction of an array.

Format
<array value constructor> ::=
<array value constructor by enumeration>
| <array value constructor by query>

[...]

<array value constructor by query> ::=
ARRAY <table subquery>

Syntax Rules
[...]
3) If <array value constructor by query> is specified, then
a) The <query expression> QE simply contained in the <table subquery> shall be 
of degree 1 (one). Let ET be the declared type of the column in the result of 
<query expression>.
b) The declared type of the <array value constructor by query> is array with 
element type ET and maximum cardinality equal to the implementation-defined 
maximum cardinality IMDC for such array types.
{code}

Proposed solution is to return an array of scalars (e.g. INTEGER ARRAY) when 
the query returns 1 column, and continue to return an array of ROW when the 
query has 2 or more columns. And do the same for MULTISET.


> ARRAY function should return an array of scalars if subquery returns 1 column
> -----------------------------------------------------------------------------
>
>                 Key: CALCITE-4999
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4999
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Dmitry Sysolyatin
>            Assignee: Dmitry Sysolyatin
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> At the moment `array` function returns [RecordType ARRAY] if subquery is 
> passed like an argument.
> {code:java}
> SELECT array(select 'toast.' || x from unnest(ARRAY['1','2']) x){code}
> But Sql standard says:
> {code:java}
> 6.38 <array value constructor>
> Function
> Specify construction of an array.
> Format
> <array value constructor> ::=
> <array value constructor by enumeration>
> | <array value constructor by query>
> [...]
> <array value constructor by query> ::=
> ARRAY <table subquery>
> Syntax Rules
> [...]
> 3) If <array value constructor by query> is specified, then
> a) The <query expression> QE simply contained in the <table subquery> shall 
> be of degree 1 (one). Let ET be the declared type of the column in the result 
> of <query expression>.
> b) The declared type of the <array value constructor by query> is array with 
> element type ET and maximum cardinality equal to the implementation-defined 
> maximum cardinality IMDC for such array types.
> {code}
> Proposed solution is to return an array of scalars (e.g. INTEGER ARRAY) when 
> the query returns 1 column, and continue to return an array of ROW when the 
> query has 2 or more columns. And do the same for MULTISET.



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