Thread: Question about array_to_string()'s behavior and the behavior mightbe changed in the future or not

Hi, 

I have a question about array_to_string(). 
I think array_to_string() concatenates always array elements from the "beginning" of the array elements and this rule
willnot be changed on the future minor releases. 
 
Is my understanding correct? 

For example, I understand that array_to_string() "never" output like following result now and in the future, is my
understandingcorrect? 
 

[Example] -> array_to_string(ARRAY[1, 2, 3, NULL, 5], ',', '*')
[Result]  -> 2,1,3,*,5

Currently I use PostgreSQL 9.5. 

Regards,

--
Yusuke, Egashira




>>>>> "Egashira" == Egashira, Yusuke <egashira.yusuke@jp.fujitsu.com> writes:

 Egashira> Hi, 
 Egashira> I have a question about array_to_string(). 

 Egashira> I think array_to_string() concatenates always array elements
 Egashira> from the "beginning" of the array elements and this rule will
 Egashira> not be changed on the future minor releases.

 Egashira> Is my understanding correct? 

The order of elements in the original array will always be preserved in
the string output, yes.

 Egashira> For example, I understand that array_to_string() "never"
 Egashira> output like following result now and in the future, is my
 Egashira> understanding correct?

Yes.

-- 
Andrew (irc:RhodiumToad)


Hi, Andrew

Thank you for immediate replying.
I'm relieved.

Regards.
--
Yusuke, Egashira

-----Original Message-----
From: Andrew Gierth [mailto:andrew@tao11.riddles.org.uk] 
Sent: Thursday, January 17, 2019 3:56 PM
To: Egashira, Yusuke/江頭 勇佑 <egashira.yusuke@jp.fujitsu.com>
Cc: 'pgsql-general@postgresql.org' <pgsql-general@postgresql.org>
Subject: Re: Question about array_to_string()'s behavior and the behavior might be changed in the future or not

>>>>> "Egashira" == Egashira, Yusuke <egashira.yusuke@jp.fujitsu.com> writes:

 Egashira> Hi, 
 Egashira> I have a question about array_to_string(). 

 Egashira> I think array_to_string() concatenates always array elements
 Egashira> from the "beginning" of the array elements and this rule will
 Egashira> not be changed on the future minor releases.

 Egashira> Is my understanding correct? 

The order of elements in the original array will always be preserved in
the string output, yes.

 Egashira> For example, I understand that array_to_string() "never"
 Egashira> output like following result now and in the future, is my
 Egashira> understanding correct?

Yes.

-- 
Andrew (irc:RhodiumToad)