Re: why do i get 2 as answer for select length('aa '::char(6));
| От | john snow |
|---|---|
| Тема | Re: why do i get 2 as answer for select length('aa '::char(6)); |
| Дата | |
| Msg-id | CAE67tvW9_tjMPJE-p3cJw_bw6JtnV8NAAY9JXwYy8x2Lhc++nQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: why do i get 2 as answer for select length('aa '::char(6)); ("David G. Johnston" <david.g.johnston@gmail.com>) |
| Список | pgsql-novice |
thanks!
you might have just missed my other post, but could i trouble you for additional info (if you have any) re:
select length('aa '::varchar(6)); //answers 6
select char_length('aa '::varchar(6)); //answers 6
select char_length('aa '::char(6)); //answers 2 even though the input string has 6 characters as was the case with the varchar input string
select length('aa '::char(6)); //answers 2 even though the input string has 6 characters as was the case with the varchar input string
are the results as expected? the last two strike me as unexpected
On Wed, Jan 17, 2018 at 10:52 AM, David G. Johnston <david.g.johnston@gmail.com> wrote:
On Tuesday, January 16, 2018, john snow <ofbizfanster@gmail.com> wrote:as well as select length('aa'::char(6));i thought if the string to be stored is shorter than specified length , it will be padded with spaces?i'm using version 10.0 on windows 10The docs could use more detail here but in short the sentence:However, trailing spaces are treated as semantically insignificant and disregarded when comparing two values of typecharacter.In turn results in the length test only counting semantically significant spaces and thus returning two regardless of the number of input spaces originally present. postgreSQL pads the spaces but then basically pretends they don't exist except for printing.I'm not sure why it even bothers to store the spaces given that...but I suppose it's more efficient than looking up the typmod all of the time.David J.
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