Hi SimonPratt,

Hm, I sort of disagree. It is very rarely (well almost never) a bad idea to use a profiling tool when your code is running too slow. It is a known fact that developers are notoriously bad at figuring out where the code is slow without using a profiling tool.

And, basically, if you double the speed of a procedure or function that takes only 10% of the overall execution time, then your win will be about 5%, i.e. nothing substantial. And that happens very frequently. So it is really better to concentrate of the parts of the code that are really slow. Perhaps it is not what you think. Perhaps it is a single line of code that is really poorly designed, and you won't know until you test it.

So, even though I also have the general feeling, in the case in point, that the performance problem is probably with the database (and the autocommit, commit rate, transaction control, redo logs, and so on), you can't be sure until you have profiled your code. To me, the 30% improvement obtained by the original poster is quite small. In my experience, real performance breakthroughs are much higher (one to two orders of magnitude).

In short, if you don't have a performance problem, it is probably useless to optimize. But if you do have a performance problem, using a profiling tool (even a very limited one) is usually better than shooting in the dark.

I am working on a proprietary language for accessing a very large database. That language has no profiling tools. I was asked to improve performance of our extraction programs. After having become pi**ed off at manually modifying programs to find out where they spent a lot of time, I wrote a little Perl program that would modify our program sources in that language in order to get a detailed account of where the program was spending a lot of time. I am really happy that I did that and I wish I had done that earlier. Now, I know immediately if and where I can improve those programs.

In brief, if you have a performance problem, I do not think that profiling the code can ever be a mistake.

In reply to Re^3: How to optimise " csv into mysql " using TEXT:CSV_XS and DBD::Mysql by Laurent_R
in thread How to optimise " csv into mysql " using Text:CSV_XS and DBD::Mysql by taiko

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