Обсуждение: Style of file error messages

Just to get an opinion, which is better:

could not open transaction log file "%s": %m
could not open control file "%s": %m
could not open data file "%s": %m
could not open temporary file "%s": %m
could not open whatever file "%s": %m

or just:

could not open file "%s": %m

It seems to me that by the time you get to a file error message of this 
level, the higher-level purpose of the file is pretty irrelevant.  
(Specific exceptions might exist.)  Log analysis tools might also 
prefer a uniform format.

Anyway, some consistency either way would be nice.

-- 
Peter Eisentraut
http://developer.postgresql.org/~petere/

Peter Eisentraut wrote:
> Just to get an opinion, which is better:
> 
> could not open transaction log file "%s": %m
> could not open control file "%s": %m
> could not open data file "%s": %m
> could not open temporary file "%s": %m
> could not open whatever file "%s": %m
> 
> or just:
> 
> could not open file "%s": %m
> 
> It seems to me that by the time you get to a file error message of this 
> level, the higher-level purpose of the file is pretty irrelevant.  
> (Specific exceptions might exist.)  Log analysis tools might also 
> prefer a uniform format.
> 
> Anyway, some consistency either way would be nice.

Since we use a relative path to $PGDATA I think that:

could not open file "%s" : %m

is plenty.

Sincerely,

Joshua D. Drake


> 


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Peter Eisentraut <peter_e@gmx.net> writes:
> Just to get an opinion, which is better:
> could not open whatever file "%s": %m
> or just:
> could not open file "%s": %m

> It seems to me that by the time you get to a file error message of this 
> level, the higher-level purpose of the file is pretty irrelevant.  

I like the more verbose variant myself, and would argue that indeed our
message style guidelines mandate it:
45.3.9. Type of the object
When citing the name of an object, state what kind of object it is.
Rationale: Otherwise no one will know what "foo.bar.baz" refers to.

A seasoned developer might only need the file name to guess what kind of
file it is, but other people could probably use the help.
        regards, tom lane

"Tom Lane" <tgl@sss.pgh.pa.us> writes:

> A seasoned developer might only need the file name to guess what kind of
> file it is, but other people could probably use the help.

I think Peter's argument is that what kind of file it is really doesn't help a
regular user. Nonetheless I agree strongly. Even if it doesn't actually make
any practical difference it's one less thing to wonder about and one more
anchor for a user to hold onto when trying to understand what's going on. 

I know I feel better knowing what part is actually broken on my car than just
having a dummy light come on even if I'm going to go to the same garage either
way.

--  Gregory Stark EnterpriseDB          http://www.enterprisedb.com

Gregory Stark wrote:
> "Tom Lane" <tgl@sss.pgh.pa.us> writes:
> 
>> A seasoned developer might only need the file name to guess what kind of
>> file it is, but other people could probably use the help.
> 
> I think Peter's argument is that what kind of file it is really doesn't help a
> regular user. Nonetheless I agree strongly. Even if it doesn't actually make
> any practical difference it's one less thing to wonder about and one more
> anchor for a user to hold onto when trying to understand what's going on. 
> 
> I know I feel better knowing what part is actually broken on my car than just
> having a dummy light come on even if I'm going to go to the same garage either
> way.

In general I agree with your assessment but... In PostgreSQL everything 
is structured so formally in terms of the filesystem that the verbosity 
seems overkill. I mean think about it:

pg_clog/0FEa
pg_xlog/9283521535
base/124765/23569.1

It isn't really that opaque. Besides, *anybody* who gets the errors we 
are talking about is going to post that they can't open the specific 
file right?

Sincerely,

Joshua D. Drake




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