Web Designer vs Web Developer

I have received a blog link from one of the members of Cebu Graphic Artists in yahoogroups. With his article, I can see that he can write very well and can present his ideas properly with good vocabulary and grammar, and I was a bit curious since rarely I could see a graphic artist who can do that. So I ran a quick search of his profile on friendster.com and verified his love for writing; he's a bookworm per se.

His article is lengthy for me, and without reading the whole of it, one could say that he's quite good, no doubt about it. I continued reading since he'd mentioned about web development. Somewhere in his article, I have read the line "...I feel that in order to be a more effective web designer, I needed to get really friendly with mySQL and PHP..." The first thing that comes to my mind was "Damn! What does PHP have anything to do with web designing?" For me, he was like saying that no artists can be really effective unless they know how to do PHP.

I was thinking that maybe this guy was a newbie with Web Designing and Development, and so I commented on his article--not on his blog, but on the mailing list. I said that PHP has nothing to do with his skills on creating web designs. If he wants to be an effective web designer, he has to deal with CSS, or maybe go deeper with Javascript so he can work on with DHTML and action scripting. Therefore, to be an effective web designer, one has to learn the essentials of Web Designing, not the essentials of Programming. There's nothing wrong in learning other things, but with his statement, that was really a misconception. I was a bit surprised with his reply though. My intention was not to insult or discredit him, but to help him see the light on becoming an effective web designer. Instead, he seemed to be embarrassed and began defending his thoughts the wrong way. My respect for him as a writer was gone, and I have realized that he can write well in English but doesn't make sense at all.

SQL Lock

One of the mailing lists that I have been a member of, has been seeking assistance to the best approach in preventing 2 or more simultaneous access to a record from a database. One member suggested the use of LAST_INSERT_ID() (for MySLQ), another one suggested of using a global variable (auto-increment), and the inquirer has resorted to the use of transactions. Among the three solutions presented, I prefer on using transactions since for me it was the most reliable.

We all know that transactions can degrade performance as it creates an overhead for each request. So I came to a solution that uses transactions but with optimized performance. I based it on the SingleTon pattern. Here's what I presented to the group in pseudo-code:


id = (SELECT ID from Table1 where ID = Id_value and ProcessID = NULL)

if (id > 0)
{

LOCK {   id = (SELECT ID from Table1 where ID = Id_value and ProcessID = NULL) UPDATE Table1 SET ProcessID = (function to get the unique identifier) where ID = id }

}

Now, we will examine the codes one by one.

The first step, "id = (SELECT ID from Table1 where ID = Id_value and ProcessID = NULL)," will try to fetch the record.

The second step, "if (id > 0)," will check if the record has already been selected. If the record has already been tagged as fetched, then the request will terminate immediately.

The third step, "LOCK," will try to execute the request one at a time. This step is very essential for programs running with threads. This is the only place where transactions should be used, and we save extra overhead by checking on step#2.

The fourth step, "id = (SELECT ID from Table1 where ID = Id_value and ProcessID = NULL)," would seem to be as a redundant statement, right? You might think that it's not necessary, but it is for multi threading. Let us say you ran 100 threads. The top 10 threads have entered the "if" statement since the initial value of ProcessID is NULL. Though 10 threads have entered the "if" statement, they're executed one by one inside the block. Here's where step#4 is of importance. It will double-check if the record was already taken from one of the 10 threads that have entered the "if" statement.

On the fifth step, "UPDATE Table1 SET ProcessID = (function to get the unique identifier) where ID = id," it will tag the record as unavailable.