i am having serious performance problems (queries up to 55 seconds) while running a mysql query since i added a group_concat clause. my query looks like: select ... group_concat(distinct category.name) .... from page where left outer join page_category on page.id = page_category.page_id left outer join category on page_category.cat...
What techniques can be applied effectively to improve the performance of SQL queries? Are there any general rules that apply? ...
I am working with a PC based automation software package called Think'n'Do created by Phoenix Contact It does real time processing, read inputs/ control logic / write outputs all done in a maximum of 50ms. We have an OPC server that is reading/writing tags from a PLC every 10ms. There is a long delay in writing a tag to the PLC and readi...
To experiment, I've (long ago) implemented Conway's Game of Life (and I'm aware of this related question!). My implementation worked by keeping 2 arrays of booleans, representing the 'last state', and the 'state being updated' (the 2 arrays being swapped at each iteration). While this is reasonably fast, I've often wondered about how to...
I am about to start testing an intranet web application. Specifically, I have to determine the application's performance. Please could somone suggest formal/informal standards for how I can judge the application's performance. ...
What is the best way to measure exception handling overhead/performance in C++? Please give standalone code samples. I'm targeting Microsoft Visual C++ 2008 and gcc. I need to get results from the following cases: Overhead when there are no try/catch blocks Overhead when there are try/catch blocks but exceptions are not thrown Overh...
I found some wild remarks that ASP.NET MVC is 30x faster than ASP.NET WebForms. What real performance difference is there, has this been measured and what are the performance benefits. This is to help me consider moving from ASP.NET WebForms to ASP.NET MVC. ...
What is a good (and preferably simple) way to test the rendering performance of WPF custom controls? I have several complex controls in which rendering performance is highly crucial. I want to be able to make sure that I can have lots of them drawwing out in a designer with a minimal impact on performance. ...
I have been told that there is a performance difference between the following code blocks. foreach (Entity e in entityList) { .... } and for (int i=0; i<entityList.Count; i++) { Entity e = (Entity)entityList[i]; ... } where List<Entity> entityList; I am no CLR expect but from what I can tell they should boil down to basi...
My app has many controls on its surface, and more are added dynamically at runtime. Although i am using tabs to limit the number of controls shown, and double-buffering too, it still flickers and stutters when it has to redraw (resize, maximize, etc). What are your tips and tricks to improve WinForms app performance? ...
I've been unable to find a source for this information, short of looking through the Python source code myself to determine how the objects work. Does anyone know where I could find this online? ...
I have a Visual Studio 2005 Solution workspace which in turn has 8 projects included in it. I want to profile the complete code(all the projects) and get some measure about the absolute cycles taken by each function to execute, or at least percentage cycle consumptions. I checked out help for VS 2005, and also the project setiings optio...
Hi I am looking for a way to create an int\long representation of an arbitrary alpha-numeric String. Hash codes won't do it, because I can't afford hash collisions i.e. the representation must be unique and repeatable. The numeric representation will be used to perform efficient (hopefully) compares. The creation of the numeric key wi...
I'm looking for any way that I can improve the selector performance of a jQuery call. Specifically things like this: Is $("div.myclass") faster than $(".myclass") I would think it might be, but I don't know if jQuery is smart enough to limit the search by tag name first, etc. Anyone have any ideas for how to formulate a jQuery select...
I am trying to improve the performance of a web application. I have metrics that I can use to optimise the time taken to return the main HTML page, but I'm concerned about the external CSS and Javascript files that are included from these HTML pages. These are served statically, with HTTP Expires headers, but are shared between all the...
Can anyone explain this behavior or how to get around it? If you execute this query: select * from TblA left join freetexttable ( TblB, *, 'query' ) on TblA.ID = [Key] inner join DifferentDbCatalog.dbo.TblC on TblA.ID = TblC.TblAID It will be very very very slow. If you change that query to use two inner joins instead of a left joi...
Consider the following 2 queries: select tblA.a,tblA.b,tblA.c,tblA.d from tblA where tblA.a not in (select tblB.a from tblB) select tblA.a,tblA.b,tblA.c,tblA.d from tblA left outer join tblB on tblA.a = tblB.a where tblB.a is null Which will perform better? My assumption is that in general the join will be better except in cases whe...
Is here any performance benefit to using multiple threads on a computer with a single CPU that does not having hyperthreading? ...
I've heard that creating a new process on a Windows box is more expensive than on Linux. Is this true? Can somebody explain the technical reasons for why it's more expensive and provide any historical reasons for the design decisions behind those reasons? ...
What are the performance, security, or "other" implications of using the following form to declare a new class instance in PHP <?php $class_name = 'SomeClassName'; $object = new $class_name; ?> This is a contrived example, but I've seen this form used in Factories (OOP) to avoid having a big if/switch statement. Problems that...