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* bit-strings with white space
@ 2018-04-18 09:55 PG Doc comments form <noreply@postgresql.org>
2018-04-22 17:18 ` Re: bit-strings with white space Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 4+ messages in thread
From: PG Doc comments form @ 2018-04-18 09:55 UTC (permalink / raw)
To: pgsql-docs@lists.postgresql.org; +Cc: pauleg.carter@gmail.com
The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/9.6/static/sql-syntax-lexical.html
Description:
Postgresql 9.6, section 4.1.2.5 says that bit-strings can spill over
multiple lines, same as regular string constants. I tried SELECTing such and
found that they may only contain characters '0' and '1'.
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: bit-strings with white space
2018-04-18 09:55 bit-strings with white space PG Doc comments form <noreply@postgresql.org>
@ 2018-04-22 17:18 ` Tom Lane <tgl@sss.pgh.pa.us>
2018-04-23 03:50 ` Re: bit-strings with white space Jim Nasby <jim@nasby.net>
0 siblings, 1 reply; 4+ messages in thread
From: Tom Lane @ 2018-04-22 17:18 UTC (permalink / raw)
To: pauleg.carter@gmail.com; +Cc: pgsql-docs@lists.postgresql.org
=?utf-8?q?PG_Doc_comments_form?= <noreply@postgresql.org> writes:
> Postgresql 9.6, section 4.1.2.5 says that bit-strings can spill over
> multiple lines, same as regular string constants. I tried SELECTing such and
> found that they may only contain characters '0' and '1'.
As indeed the text says. What the continuation mention is talking
about is this syntax:
regression=# select b'10001'
'00100';
?column?
------------
1000100100
(1 row)
which works like
regression=# select 'foo'
'bar';
?column?
----------
foobar
(1 row)
Perhaps there's something we could change to make this clearer,
but I'm not sure what.
regards, tom lane
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: bit-strings with white space
2018-04-18 09:55 bit-strings with white space PG Doc comments form <noreply@postgresql.org>
2018-04-22 17:18 ` Re: bit-strings with white space Tom Lane <tgl@sss.pgh.pa.us>
@ 2018-04-23 03:50 ` Jim Nasby <jim@nasby.net>
2018-04-23 04:07 ` Re: bit-strings with white space David G. Johnston <david.g.johnston@gmail.com>
0 siblings, 1 reply; 4+ messages in thread
From: Jim Nasby @ 2018-04-23 03:50 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; pauleg.carter@gmail.com; +Cc: pgsql-docs@lists.postgresql.org
On 4/22/18 12:18 PM, Tom Lane wrote:
> regression=# select 'foo'
> 'bar';
> ?column?
> ----------
> foobar
> (1 row)
>
> Perhaps there's something we could change to make this clearer,
> but I'm not sure what.
I had no idea you could do that. While there's probably some wordy
description that could explain this, I think an example is probably the
best bet. Are there any other data types that work like this?
--
Jim C. Nasby, Data Architect jim@nasby.net
512.569.9461 (cell) http://jim.nasby.net
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: bit-strings with white space
2018-04-18 09:55 bit-strings with white space PG Doc comments form <noreply@postgresql.org>
2018-04-22 17:18 ` Re: bit-strings with white space Tom Lane <tgl@sss.pgh.pa.us>
2018-04-23 03:50 ` Re: bit-strings with white space Jim Nasby <jim@nasby.net>
@ 2018-04-23 04:07 ` David G. Johnston <david.g.johnston@gmail.com>
0 siblings, 0 replies; 4+ messages in thread
From: David G. Johnston @ 2018-04-23 04:07 UTC (permalink / raw)
To: Jim Nasby <jim@nasby.net>; +Cc: Tom Lane <tgl@sss.pgh.pa.us>; pauleg.carter@gmail.com <pauleg.carter@gmail.com>; pgsql-docs@lists.postgresql.org <pgsql-docs@lists.postgresql.org>
On Sunday, April 22, 2018, Jim Nasby <jim@nasby.net> wrote:
> On 4/22/18 12:18 PM, Tom Lane wrote:
>
>> regression=# select 'foo'
>> 'bar';
>> ?column?
>> ----------
>> foobar
>> (1 row)
>>
>> Perhaps there's something we could change to make this clearer,
>> but I'm not sure what.
>>
>
> I had no idea you could do that. While there's probably some wordy
> description that could explain this, I think an example is probably the
> best bet. Are there any other data types that work like this?
>
>
This structural "normalization" gets applied before types get involved.
Two literals only separated by a newline are concatenated together. Any
type name prefix, E or b prefix, :: cast, or cast() application then gets
applied to the combined literal.
The sql syntax section on this could maybe use another example or two but
does communicate the behavior reasonably well.
https://www.postgresql.org/docs/10/static/sql-syntax-lexical.html#SQL-SYNTAX-CONSTANTS
David J.
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2018-04-22 17:18 ` Tom Lane <tgl@sss.pgh.pa.us>
2018-04-23 03:50 ` Jim Nasby <jim@nasby.net>
2018-04-23 04:07 ` David G. Johnston <david.g.johnston@gmail.com>
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