From: Tom Lane <tgl@sss.pgh.pa.us>
To: "David G. Johnston" <david.g.johnston@gmail.com>
cc: =?UTF-8?B?55SE5piO5rSL?= <zhenmingyang@yeah.net>,
        "pgsql-bugs@postgresql.org" <pgsql-bugs@postgresql.org>
Subject: Re: setting the timezone parameter with space cause diff result
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Comments: In-reply-to "David G. Johnston" <david.g.johnston@gmail.com>
	message dated "Tue, 08 Jun 2021 19:46:18 -0700"
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Date: Tue, 08 Jun 2021 23:20:50 -0400
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"David G. Johnston" <david.g.johnston@gmail.com> writes:
> On Tuesday, June 8, 2021, 甄明洋 <zhenmingyang@yeah.net> wrote:
>> Here is an example, which seems to be a problem of parsing, if format
>> string with FF and TZH:TZM,  but the datetime string without fractional
>> seconds will cause parsing misalignment，

> Yes, with a template language this complex it is possible that invalid
> input will mis-parse instead of provoking an error.  Use regexes if you
> need to validate the input format - all the parser should really be relied
> upon to do is take a valid input and convert it.

TBH, if we simply took away to_timestamp(), most users would be better off.
I do not think I've ever seen a single complaint about it that didn't
involve an input format that timestamp_in doesn't handle as well or
better.

to_timestamp with a normal-looking format is an antipattern.  Just cast
the string to timestamp(tz), instead.  Consider to_timestamp *only*
after you find that doesn't work.

			regards, tom lane