Foreign Keys are a referential integrity tool, not a performance tool. At least in SQL Server, the creation of an FK does not create an associated index, and you should create indexes on all FK fields to improve look up times.
Order of magnitude: zero. In other words, you won’t see your throughput cut in half, or anything like it, when you add TLS. Answers to the “duplicate” question focus heavily on application performance, and how that compares to SSL overhead. This question specifically excludes application processing, and seeks to compare non-SSL to SSL only. While … Read more
Regardless of compiler, you can always save on runtime if you can afford to do if (typeid(a) == typeid(b)) { B* ba = static_cast<B*>(&a); etc; } instead of B* ba = dynamic_cast<B*>(&a); if (ba) { etc; } The former involves only one comparison of std::type_info; the latter necessarily involves traversing an inheritance tree plus comparisons. … Read more
IEnumerable<T>.ToList() Yes, IEnumerable<T>.ToList() does have a performance impact, it is an O(n) operation though it will likely only require attention in performance critical operations. The ToList() operation will use the List(IEnumerable<T> collection) constructor. This constructor must make a copy of the array (more generally IEnumerable<T>), otherwise future modifications of the original array will change on … Read more
This is because: It increases the parallelism available. (Most browsers will only download 3 or 4 files at a time from any given site.) It increases the chance that there will be a cache-hit. (As more sites follow this practice, more users already have the file ready.) It ensures that the payload will be as … Read more
Your QuickRandom implementation hasn’t really an uniform distribution. The frequencies are generally higher at the lower values while Math.random() has a more uniform distribution. Here’s a SSCCE which shows that: package com.stackoverflow.q14491966; import java.util.Arrays; public class Test { public static void main(String[] args) throws Exception { QuickRandom qr = new QuickRandom(); int[] frequencies = new … Read more
A value of the double floating-point type is represented like so: and it can be seen as two 32-bit integers; now, the int taken in all the versions of your code (supposing it’s a 32-bit int) is the one on the right in the figure, so what you are doing in the end is just … Read more
The cache is there to reduce the number of times the CPU would stall waiting for a memory request to be fulfilled (avoiding the memory latency), and as a second effect, possibly to reduce the overall amount of data that needs to be transfered (preserving memory bandwidth). Techniques for avoiding suffering from memory fetch latency … Read more
There are two perf problems induced by the Point struct. Something you can see when you add Console.WriteLine(GC.CollectionCount(0)); to the test code. You’ll see that the Point test requires ~3720 collections but the string test only needs ~18 collections. Not for free. When you see a value type induce so many collections then you need … Read more
You can use the PHP function apc_clear_cache. Calling apc_clear_cache() will clear the system cache and calling apc_clear_cache(‘user’) will clear the user cache.