Hi, We have runned into a problem with an sp. We have a pretty simple sp containing a declared table and a couple of outer joins that in the end returns between 20 and 100 rows. Since querying this sp has been giving us poor performance both in production and in testenvironment we recently rewrote it to be more efficient and has teste...
I use a view based on a complex query with 17 joins (both inner and left/right outer) and subqueries. All view rows are shown in about 5 seconds. SELECT * FROM a_view; One of the view columns has type BIT. And when I filter view rows comparing it with 1, a query works again about 5 seconds. SELECT * FROM a_view WHERE c = 1; But wh...
Is there a difference in performance between TOP and SET ROWCOUNT or do they just get executed in the same manner? ...
Edit: I apologize everybody. I used the term "jagged array" when I actually meant to say "multi-dimensional array" (as can be seen in my example below). I apologize for using the incorrect name. I actually found jagged arrays to be faster than multi-dimensional ones! I have added my measurements for jagged arrays. I was trying to use a ...
Just wondering if anyone knew off the top of their heads if there was much difference in doing the following: String wibble = "<blah> blah blah </blah>.... <wibble> blah wibble blah </wibble> some more test here"; int i = wibble.lastIndexOf(">"); int j = wibble.lastIndexOf('>'); ...
I'm debating about whether to learn GP-GPU stuff, such as CUDA, or whether to put it off. My problem domain (bioinformatics) is such that it might be nice to know, since a lot of our problems do have massive parallelism, but most people in the field certainly don't know it. My question is, how difficult the API for CUDA and other GP-GP...
How much of a bottleneck is memory allocation/deallocation in typical real-world programs? Answers from any type of program where performance typically matters are welcome. Are decent implementations of malloc/free/garbage collection fast enough that it's only a bottleneck in a few corner cases, or would most performance-critical softw...
I browse to a web page that has a javascript memory leak. If I refresh the page multiple times, it will eventually use up a significant amount of memory, and javascript on the page will slow down. On this particular page, I notice a very significant slow down when IE gets up to 100MB of RAM, even though I have multiple GB free. My ques...
I come from a DBA world and performance has always been an obsession. I am turning to development and I always think about performance, constantly, all the time. Reading on SO sometimes seems that performance does not matter. For instance for evangelists on hibernate (or any other ORM). As a developer, when do I have to think about per...
I have a Java program consisting of about 15 methods. And, these methods get invoked very frequently during the exeuction of the program. At the moment, I am creating a new connection in every method and invoking statements on them (Database is setup on another machine on the network). What I would like to know is: Should I create only...
I have a benchmarking application to test out the performance of some APIs that I have written. In this benchmarking application, I am basically using the QueryPerformanceCounter and getting the timing by dividing the difference of QPC values after and before calling into the API, by the frequency. But the benchmarking results seems to v...
Some time ago I wrote a little piece of code to ask about on interviews and see how people understand concepts of cache and memory: #include "stdafx.h" #include <stdlib.h> #include <windows.h> #include <iostream> #define TOTAL 0x20000000 using namespace std; __int64 count(int INNER, int OUTER) { int a = 0; int* arr = (int*) H...
I've just come across a database where all the character based columns have their size specified in multiples of 8 (e.g. Username = varchar(32), Forename = nvarchar(128) etc.) Would this have any bearing on the performance of the database or is it completely pointless? Thanks. N.B. This is in a SQL 2000 database. ...
Context My current project is a large-ish public site (2 million pageviews per day) site running a mixture of asp classic and asp.net with a SQL Server 2005 back-end. We're heavy on reads, with occasional writes and virtually no updates/deletes. Our pages typically concern a single 'master' object with a stack of dependent (detail) obje...
I've seen once on a site, a call graph digging into the most low level libraries of a web request initiated by a PHP appplication with call timings and summary. Seems to me that this is a great way to spot the reason of bottlenecks that aren't obvious while profiling PHP-only code. Something like strace does but with far more detail. ...
In attempting to use the Performance Tools on an ASP.NET website I'm getting various combinations of these errors (depending on what I attempt to do to fix them): The web site could not be configured correctly. Configuring '\web.config' failed. Access to the path '\web.config' is denied. - I can make this dissappear by checking-out the...
Anyone who reads a lot of SO questions knows that the need to preach against premature optimization is not going away anytime soon - but what about the other extreme, the projects that fail or struggle because they did not consider performance early enough? Should you just try and get a working system as quickly as possible so you can d...
I am involved in a venture that will port some communications, parsing, data handling functionality from Win32 to Linux and both will be supported. The problem domain is very sensitive to throughput and performance. I have very little experience with performance characteristics of boost and ACE. Specifically we want to understand wh...
I need to think about performance limitations of 100 mbps ethernet (including scenarios with up to ~100 endpoints on the same subnet) and I'm wondering how best to go about estimating the capacity of the network. Are there any rules of thumb for this? The reason I ask is that I am working on some back-of-the-envelope level calculations ...
If I understand this correctly: Current CPU developing companies like AMD and Intel have their own API codes (the assembly language) as what they see as the 2G language on top of the Machine code (1G language) Would it be possible or desirable (performance or otherwise) to have a CPU that would perform IL handling at it's core instead...