practical limit on the number of UIDs

[Shachar Shemesh]

On 29/06/11 12:01, Muli Ben-Yehuda wrote:
> On Wed, Jun 29, 2011 at 11:43:00AM +0300, Tom Goren wrote:
>
>> Sounds like a job better suited for a DB backed authentication
>> system such as LDAP.
>>
>> This is just off the top of my head, but for some reason I wouldn't
>> want /etc/passwd and its relatives 1 million lines long.
> I shared the same instinctive response and am now trying to find hard
> data (ok, anecdotal data) to support it.
>
Often, when engineers ask a question, they seem to forget that their 
baseline of comparison, most often manual labor, is not perfect either. 
The most obvious example is NLP (natural language processing), where 
when evaluating the accuracy of an NLP engine one should always remember 
that humans parsing (reading) text have, on average, an accuracy of only 
97% (down to 50% if text received via email, for some reason :-).

When you reach so many users, the problems relating to questions such as 
"how long does it take nss to parse /etc/passwd" start to be dwarfed by 
the human cost of maintaining a megaline text file. If for that reason 
alone, you will need to switch to a DB back end.

I will remind you that when we opened Hamakor, we tried to manage the 
list of members in a hand written CSV. At less than 20 members, the file 
was no longer well formed and machine parseable. Text files are simply 
not up to that task, regardless of parsing costs. An admin mistake will 
wreak such havoc that it is simply impossible to reach that stage 
anyways, and the core question is, IMHO, moot.

Shachar

-- 
Shachar Shemesh
Lingnu Open Source Consulting Ltd.
http://www.lingnu.com