I had a similar problem with several lookup tables joining to a large table with all id fields indexed. To monitor the effect of the joins on query time execution, I ran my query several times (limiting to first 100 rows), adding a Join to an additional table each time. After joining 12 tables, there … Read more
This is a great question. First of all, here are a couple of workarounds that come to mind (they all require changes to the query): First workaround This one maybe a bit obvious and unfortunately not generally applicable: If the selection of items you would need to pass over to Enumerable.Contains already exists in a … Read more
It turns out that when you compile without the -fPIC option multiplyComplex, sqComplex, isInSet and isMandelbrot are inlined automatically by the compiler. If you define those functions as static you will likely get the same performance when compiling with -fPIC because the compiler will be free to perform inlining. The reason why the compiler is … Read more
It’s all about which you find the most readable. Of course, this will vary with each situation. If you were doing an entire page, and there were large sections which did not have any PHP in it, then I’d break out of PHP and just write the plain HTML, whereas if there was a section … Read more
SET is the ANSI standard way of assigning values to variables, and SELECT is not. But you can use SELECT to assign values to more than one variable at a time. SET allows you to assign data to only one variable at a time. So that in performance is where SELECT will be a winner. … Read more
SET is the ANSI standard way of assigning values to variables, and SELECT is not. But you can use SELECT to assign values to more than one variable at a time. SET allows you to assign data to only one variable at a time. So that in performance is where SELECT will be a winner. … Read more
From IEEE 1003.1: The mmap() function shall establish a mapping between a process’ address space and a file, shared memory object, or [TYM] typed memory object. It needs all the virtual address space because that’s exactly what mmap() does. The fact that it isn’t really running out of memory doesn’t matter – you can’t map … Read more
The API to control network emulation were added to ChromeDriver. And should be available for quite a while now. According to comment in the linked issue you should use version at least 2.26 because of some bugfix. According to Selenium changelog bindings are available for these languages: JavaScript as of version 3.4.0 (commit) Python as … Read more
pow() works with real floating-point numbers and uses under the hood the formula pow(x,y) = e^(y log(x)) to calculate x^y. The int are converted to double before calling pow. (log is the natural logarithm, e-based) x^2 using pow() is therefore slower than x*x. Edit based on relevant comments Using pow even with integer exponents may … Read more
deque.popleft() is faster than list.pop(0), because the deque has been optimized to do popleft() approximately in O(1), while list.pop(0) takes O(n) (see deque objects). Comments and code in _collectionsmodule.c for deque and listobject.c for list provide implementation insights to explain the performance differences. Namely that a deque object “is composed of a doubly-linked list”, which … Read more