How might I optimize this query? The schema: mysql> show columns from transactionlog; +---------------+-------------------------------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------------+-------------------------------...
I got this code, I would like to optimize. I basically can add new columns to "Disp" table later on, and I don't want to come back modify this function. I cannot use dynamic SQL. Right? Is there anything else that would work in my case? This is the function: ALTER FUNCTION [GetDate] (@hdrnumber INT, @DateColName VARCHAR(50)) RETURNS D...
I need to resample big sets of data (few hundred spectra, each containing few thousand points) using simple linear interpolation. I have created interpolation method in C# but it seems to be really slow for huge datasets. How can I improve the performance of this code? public static List<double> interpolate(IList<double> xItems, ILi...
I need to perform a bitwise equality between two bytes. That means that for instance if I have two bytes: 00011011 and 00011110 the result is 11111010 The only fast way I see is to use the following statement byte a, b;//set input bytes byte c = ~(a^b);//output bytes But I wonder if there is a faster solution for this. After these equ...
This query originally came from a VB6 program accessing MS Access tables which are linked to external databases through ODBC. It takes about 3:30 to run. Now I've setup a SQL Server 2008 Express box to evaluate how we can migrate to a better database system. So I setup a linked server to the external server (we call it DWPROD) and when ...
(I'm using prototype.js here, but I imagine the same holds true across other libraries as well) I often find myself writing code like this: var search_box; Event.observe(window, 'load', function() { search_box = $('search_box'); }); function doSomething(msg) { search_box.innerHTML = msg; } Rather then writing it simply like...
I'm building a CGI script that polls a SQLite database and builds a table of statistics. The source database table is described below, as is the chunk of pertinent code. Everything works (functionally), but the CGI itself is very slow as I have multiple nested SELECT COUNT(id) calls. I figure my best shot at optimization is to ask the SO...
I am somewhat familiar with the CUDA visual profiler and the occupancy spreadsheet, although I am probably not leveraging them as well as I could. Profiling & optimizing CUDA code is not like profiling & optimizing code that runs on a CPU. So I am hoping to learn from your experiences about how to get the most out of my code. There was...
Guys! My problem is optimizaiton of this code for IE 8 (with IE 8 first button is ok, but second doesn't work), Google Chrome (second button is ok, but first doesn't work). I've stack with it, help please. :) FIRST BUTTON <div id="spoiler"> <div> <p style="text-align: center;"><input style="margin: 10px; padding: 0px; width: 150px; fon...
Hi, I am using SQL 2000, and I am running a simple select statement on a table containing about 30 million rows. The select query looks like: select col1, col2, col3 from Table1 where col4=@col4 and col5=@col5 and col6=@col6 The table has a clustered index in it (i.e. a primary key), but that is not being used as a where criteria. All...
I have a situation in my application. For each x-axis point in my chart, I am plotting 5 y-axis values. To calculate each of these 5 values, I need to make 4 different queries. Ie, for each x-axis point I need to fire 20 sql queries. Now, I need to plot 40 such points in the my chart. Its resulting in a pathetic performance where it ta...
I've seen this blog: http://igoro.com/archive/gallery-of-processor-cache-effects/ The "weirdness" in part 7 is what caught my interest. My first thought was "Thats just C# being weird". Its not I wrote the following C++ code. volatile int* p = (volatile int*)_aligned_malloc( sizeof( int ) * 8, 64 ); memset( (void*)p, 0, sizeof( int ...
I'm using Hibernate to work on a new project, and as I work I'm realizing that my original vision for the application may not end up being its destiny. Data that I think is not going to be often requested (and thus lazy-loaded) might end up being needed for 85% of requests. Conversely, data that I'm loading under the assumption it will b...
I need to update my contacts database in SQL Server with changes made in a remote database (also SQL Server, on a different server on the same local network). I can't make any changes to the remote database, which is a commercial product. I'm connected to the remote database using a linked server. Both tables contain around 200K rows. M...
The table contains about 40,000,000 records having: CREATE TABLE `event` ( `id` bigint(20) unsigned NOT NULL auto_increment, `some_other_id_not_fk` int(10) unsigned default NOT NULL, `event_time` datetime NOT NULL, `radius` float default NULL, `how_heavy` smallint(6) default NULL, PRIMARY KEY (`id`), KEY `event_some_other...
I just stumbled upon a change that seems to have counterintuitive performance ramifications. Can anyone provide a possible explanation for this behavior? Original code: for (int i = 0; i < ct; ++i) { // do some stuff... int iFreq = getFreq(i); double dFreq = iFreq; if (iFreq != 0) { // do some stuff with iFre...
is there a better way to write this SQL than using WHERE ... IN (subquery)? SELECT device.mac, reseller.name, agent.name FROM device LEFT JOIN global_user ON device.global_user_id = global_user.id LEFT JOIN agent ON global_user.id = agent.global_user_id LEFT JOIN reseller ON global_user.id = reseller.global_user_id...
I'm trying to figure out why a SQL Server stored procedure is executing slowly, so I've put in some crude timers, like this: Create Procedure DoStuff As Begin Declare @Stopwatch datetime Set @Stopwatch=GetDate() Print char(13) + 'Task A' /* Perform Task A */ Print DateDiff(ms, @Stopwatch, GetDate()); Set @Stopwatc...
What are things like survey.map(&:questions).flatten.compact called, so I can find more information about them :). What problems does that &: solve, or what is it doing exactly? Is it used in other languages? ...
Given a table: id | score | position ===================== 1 | 20 | 2 2 | 10 | 3 3 | 30 | 1 What query can I use to optimally set the position columns using the (not nullable) score column? (I'm sure I've seen this before but I can't seem to get the correct keywords to find it!) ...