From: | Chapman Flack <chap(at)anastigmatix(dot)net> |
---|---|
To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, David Fetter <david(at)fetter(dot)org> |
Cc: | PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: string_to_array, array_to_string function without separator |
Date: | 2019-03-15 15:59:01 |
Message-ID: | c16e7666-76b3-4078-0553-ae9ed0206dfb@anastigmatix.net |
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Lists: | pgsql-hackers |
On 3/15/19 11:46 AM, Pavel Stehule wrote:
> pá 15. 3. 2019 v 15:03 odesílatel David Fetter <david(at)fetter(dot)org> napsal:
>> Whatever optimizations you have in mind for this, could they also work
>> for string_to_array() and array_to_string() when they get an empty
>> string handed to them?
>
> my idea is use string_to_array('AHOJ') --> {A,H,O,J}
>
> empty input means empty result --> {}
I thought the question was maybe about an empty /delimiter/ string.
It seems that string_to_array already has this behavior if NULL is
passed as the delimiter:
> select string_to_array('AHOJ', null);
string_to_array
-----------------
{A,H,O,J}
and array_to_string has the proposed behavior if passed an
empty string as the delimiter (as one would naturally expect)
... but not null for a delimiter (that just makes the result null).
So the proposal seems roughly equivalent to making string_to_array's
second parameter optional default null, and array_to_string's second
parameter optional default ''.
Does that sound right?
Regards,
-Chap
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