Profile

Cover photo
Anatoly “Aen Sidhe” Popov
Attends ЛГТУ
111 followers|65,642 views
AboutPostsPhotosVideos

Stream

 
ТОПОРЪ via +Zu Zuzu 
 ·  Translate
5
1
Natalia “lspacca” Mikhaleva's profile photoMark Harris's profile photo
 
Носит с собой топор до того, как это станет модно.
 ·  Translate
Add a comment...
 
 
A lesson in shortcuts.

Long ago, as the design of the Unix file system was being worked out, the entries . and .. appeared, to make navigation easier. I'm not sure but I believe .. went in during the Version 2 rewrite, when the file system became hierarchical (it had a very different structure early on).  When one typed ls, however, these files appeared, so either Ken or Dennis added a simple test to the program. It was in assembler then, but the code in question was equivalent to something like this:
   if (name[0] == '.') continue;
This statement was a little shorter than what it should have been, which is
   if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0) continue;
but hey, it was easy.

Two things resulted.

First, a bad precedent was set. A lot of other lazy programmers introduced bugs by making the same simplification. Actual files beginning with periods are often skipped when they should be counted.

Second, and much worse, the idea of a "hidden" or "dot" file was created. As a consequence, more lazy programmers started dropping files into everyone's home directory. I don't have all that much stuff installed on the machine I'm using to type this, but my home directory has about a hundred dot files and I don't even know what most of them are or whether they're still needed. Every file name evaluation that goes through my home directory is slowed down by this accumulated sludge.

I'm pretty sure the concept of a hidden file was an unintended consequence. It was certainly a mistake.

How many bugs and wasted CPU cycles and instances of human frustration (not to mention bad design) have resulted from that one small shortcut about  40 years ago?

Keep that in mind next time you want to cut a corner in your code.

(For those who object that dot files serve a purpose, I don't dispute that but counter that it's the files that serve the purpose, not the convention for their names. They could just as easily be in $HOME/cfg or $HOME/lib, which is what we did in Plan 9, which had no dot files. Lessons can be learned.)
110 comments on original post
1
Add a comment...
3
Alexander Stavonin's profile photo
 
Это 5!
Add a comment...
 
Hello.

Is it possible to change primary key on table online? AFAIR, the answer is no, but may be my knowledge is outdated. Sql2012 with all updates.

So, if you know some way to do this (or how to mitigate downtime), please let me know.
1
Ken Watson's profile photoAnatoly “Aen Sidhe” Popov's profile photoUwe Ricken's profile photo
8 comments
 
Hallo Anatoly,

the I/O will only be raised when the PK will be recreated because it will create a new index for the key attribute.

The dropping will not cause a huge amount of I/O because it's pure metadata operation!

If the PK has not been created as CLUSTERED the amount of I/O will not be as much as with clustered because the recreation of a clustered index means a rebuild of the table itself.

If the table has a different clustered index it will only generate the I/O for the "new" index but not for the table itself!
Add a comment...
 
 
Весёлый спам пришёл. Рекламировать не буду, но суть в том что тебе платят какие-то копейки за запуск их ботнета на своей машине, причём это ещё и пирамида.
 ·  Translate
2 comments on original post
1
Add a comment...
Have him in circles
111 people
Milos Dzakovic's profile photo
Зоя Демьянская's profile photo
Pavel Volchenkov's profile photo
Aleksey Danshin's profile photo
Natalia “lspacca” Mikhaleva's profile photo
Lgerd Hive's profile photo
Максим Сланчевский's profile photo
Stan Lagun's profile photo
Ilya Mikheev's profile photo
 
Экранизация рассказа про совещание.
 ·  Translate
1
Vladimir Bukreev's profile photo
 
Кстати есть и русская видео-версия, ИМХО она была первая.
 ·  Translate
Add a comment...
 
Ищу настройщика фортепиано в Москве.
 ·  Translate
1
Данила Володарский's profile photoAnatoly “Aen Sidhe” Popov's profile photoAlexander Borodin's profile photo
3 comments
 
Обычно он требуется после переезда...
 ·  Translate
Add a comment...
 
#git  

Полезное. Буду рад, если кто-нибудь расскажет - почему такая фигня вообще случается.
Have had a funy problem with Git. I suppose it's proxy-related. Writing it down, because sure that will have the same problem some time again. Also hope it will help to people who are also suffering with it. As a precondition, I have a git with following in '.gitconfig': ...
1
Add a comment...
People
Have him in circles
111 people
Milos Dzakovic's profile photo
Зоя Демьянская's profile photo
Pavel Volchenkov's profile photo
Aleksey Danshin's profile photo
Natalia “lspacca” Mikhaleva's profile photo
Lgerd Hive's profile photo
Максим Сланчевский's profile photo
Stan Lagun's profile photo
Ilya Mikheev's profile photo
Basic Information
Gender
Male
Other names
Ин Ши
Education
  • ЛГТУ
    present
Links
Contributor to