SQL Server SELECT LAST N Rows
You can get SQL server to select the last N rows with the following query: select * from tbl_name order by id desc limit N;
performance
jQuery hasClass() – check for more than one class
element.is(‘.class1, .class2′) works, but it’s 35% slower than element.hasClass(‘class1’) || element.hasClass(‘class2’) See also this jsbench.me test.
Algorithm to calculate the number of divisors of a given number
Dmitriy is right that you’ll want the Sieve of Atkin to generate the prime list but I don’t believe that takes care of the whole issue. Now that you have a list of primes you’ll need to see how many of those primes act as a divisor (and how often). Here’s some python for the … Read more
Android webview slow
It depends on the web application being loaded. Try some of the approaches below: Set higher render priority (deprecated from API 18+): webview.getSettings().setRenderPriority(RenderPriority.HIGH); Enable/disable hardware acceleration: if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { // chromium, enable hardware acceleration webView.setLayerType(View.LAYER_TYPE_HARDWARE, null); } else { // older android version, disable hardware acceleration webView.setLayerType(View.LAYER_TYPE_SOFTWARE, null); } Disable the cache (if … Read more
How to deal with a slow SecureRandom generator?
You should be able to select the faster-but-slightly-less-secure /dev/urandom on Linux using: -Djava.security.egd=file:/dev/urandom However, this doesn’t work with Java 5 and later (Java Bug 6202721). The suggested work-around is to use: -Djava.security.egd=file:/dev/./urandom (note the extra /./)
Speed up millions of regex replacements in Python 3
TLDR Use this method if you want the fastest regex-based solution. For a dataset similar to the OP’s, it’s approximately 1000 times faster than the accepted answer. If you don’t care about regex, use this set-based version, which is 2000 times faster than a regex union. Optimized Regex with Trie A simple Regex union approach … Read more
Fastest way to iterate over all the chars in a String
FIRST UPDATE: Before you try this ever in a production environment (not advised), read this first: http://www.javaspecialists.eu/archive/Issue237.html Starting from Java 9, the solution as described won’t work anymore, because now Java will store strings as byte[] by default. SECOND UPDATE: As of 2016-10-25, on my AMDx64 8core and source 1.8, there is no difference between … Read more
Microsoft CDN for jQuery or Google CDN? [closed]
Update based on comments: Short version: It doesn’t matter much, but it may depend on what they host. They all host different things: Google doesn’t host jQuery.Validate, Microsoft did not host jQuery-UI, since 2016 they do!!, Microsoft offers their scripts that would otherwise be served via ScriptResource.axd and an easier integration (e.g. ScriptManager with ASP.Net … Read more
SQL, Postgres OIDs, What are they and why are they useful?
OIDs basically give you a built-in id for every row, contained in a system column (as opposed to a user-space column). That’s handy for tables where you don’t have a primary key, have duplicate rows, etc. For example, if you have a table with two identical rows, and you want to delete the oldest of … Read more
Most efficient way to concatenate strings in JavaScript?
Seems based on benchmarks at JSPerf that using += is the fastest method, though not necessarily in every browser. For building strings in the DOM, it seems to be better to concatenate the string first and then add to the DOM, rather then iteratively add it to the dom. You should benchmark your own case … Read more