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PostgreSQL: Difference between text and varchar (character varying)
... increased storage space when using the blank-padded type, and a few extra CPU cycles to check the length when storing into a length-constrained column. While character(n) has performance advantages in some other database systems, there is no such advantage in PostgreSQL; in fact character(n) is usu...
What data type to use for hashed password field and what length?
...le numerical value, others have more parameters there (for example to tune CPU usage and RAM usage separately).
The salt. Since the salt must be globally unique, it has to be stored for each account. The salt should be generated randomly on each password change.
The hash proper, i.e. the output of t...
How much faster is C++ than C#?
...ter will be competing with your code for instruction and data cache in the CPU. We know that cache dominates when it comes to performance and native languages like C++ do not have this type of contention, by definition.
a run-time optimizer's time budget is necessarily much more constrained than th...
Android destroying activities, killing processes
... persistent data, stop animations and other things that may be
consuming CPU, etc. Implementations of this method must be very quick
because the next activity will not be resumed until this method
returns. Followed by either onResume() if the activity returns back to
the front, or onStop() i...
Java HashMap performance optimization / alternative
...hat does this accomplish? Adding a constant to every hash value just burns cpu cycles without accomplishing anything useful. Lesson here: Adding complexity to a hash function is not the goal. The goal is to get a broad range of different values, not just to add complexity for the sake of complexity....
What does it mean to hydrate an object?
... for your current operations. So there's no reason to waste bandwidth and CPU cycles loading, transferring, and setting this data when it's not going to be used.
Additionally, there are some ORM's, such as Doctrine, which do not hydrate objects when they are instantiated, but only when the data is...
OS detecting makefile
...commended or ideal; they're just what the project to which I was adding OS/CPU auto-detection happened to be using.
ifeq ($(OS),Windows_NT)
CCFLAGS += -D WIN32
ifeq ($(PROCESSOR_ARCHITEW6432),AMD64)
CCFLAGS += -D AMD64
else
ifeq ($(PROCESSOR_ARCHITECTURE),AMD64)
...
Why should hash functions use a prime number modulus?
...
@SteveJessop The number 31 is easily optimized by the CPU as a (x*32)-1 operation, in which *32 is a simple bit shift, or even better an immediate address scale factor (e.g. lea eax,eax*8; leax, eax,eax*4 on x86/x64). So *31 is a good candidate for prime number multiplication. T...
Why '&&' and not '&'?
...uit is a branch/jump; which could result in a branch-misprediction on your CPU; an & is much cheaper than &&. There is also a scenario where short-circuiting can actually break logic - have a look at this answer of mine.
Diatribe/Monologue: Regarding the branch mis-prediction that most ...
What are the differences between a multidimensional array and an array of arrays in C#?
...nal but my guess is that it has to do with some optimalization made on the CPU
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