stackoverflow

Tags: sql StackOverflow de-weightproblemSuppose you have a table with a larger amount of data (for example, 300,000+ rows), where there are duplicate rows (other than the primary key, the other column data is the same), how do you quickly go heavy? My watch looks like this.MyTable-----------RowID int not null identity(1,1) primary key,Col1 varchar(20) not null,Col2 varchar(2048) not null,Col3 tinyint not nullEssence AnswerAssuming there are no null va

problemMapEssence AnswerMethod 1:Using TreeMap, you can refer to the following codepublic class Testing {public static void main (string[] args) {hashmapIf you do not write your own comparator,treemap default is to sort by keyMethod 2:public class maputil{Public static These two methods, I simply tested the next, if the map size at level 100,000 above, both time is hundreds of milliseconds, the second method will be faster. Otherwise, the first method is a little faster. So if you are dealing

problemSuppose there are arraysElement[]Array= {New Element(1),New Element(2),New Element(3)};How do you convert it to arraylistEssence Answerarrays asList array Arrays.aslist(new Element (1), new Element (2), new Element (3))However, there are some pits to be aware of:1. The list to be generated is fixed length. In other words, if you do add or remove to it, it will throw unsupportedoperationexception. 2, if you modify the value of the array, the corresponding value in the list will also

Online question and answer system for imitation stackoverflow development"Phase two November 9" Use the Python Flask Web development Framework to implement a similar stackoverflow online question and answer platform Louqa, with questions, answers, comments and other features. Learn about database design, Python Web development, and bootstrap knowledge. In the second phase of open enrolment, there is a limit

> While the best approach is still to optimize your layout, the solution nesting will not only speed up page rendering, but also solve this problem. But there is no time to optimize, you can only use this dirty way first. The last thing I used was a downgrade, because the project was tight and there was no loss, so the downgrade became the most insured option. For this imposing restriction on the 2.x system, it is true that the egg hurts!The stack size of the UI thread in Android

What is the Big O analysis of this algorithm? (Stackoverflow ), Question: I'm working on a data structures course and I'm not sure how to proceed w/this Big O analysis: sum = 0;for(i = 1; i My initial idea is that this is O (n ^ 3) after ction, because the innermost loop will only run whenj/iHas no remainder and the multiplication rule is inapplicable. Is my reasoning correct here? Answer: Let's ignore the outer loop for a second here, and let's an

size of a number. The result of the hashing algorithm is usually in the range of some large numbers, which must be much larger than the number of tables you have stored in the table. For example, we want to save 1 million of the book, then the output can be 0 to a larger number than 1 million.What do we do? With a computational model, we look for a number that is larger than the maximum range, and then we start with 0.Is the algorithm of the range is 0-20, the number of 7, we find 17, we have t

because threads and real processes are similar, but execute in the context of a process and share resources allocated by the kernel to processesUsually, a process has only one thread of control–one set of machine instructions executing at a time.A process may also is made up to multiple threads of execution that execute instructions concurrently.Multiple threads of control can exploit the true parallelism possible on multiprocessor systems.On a uni-processor system, a thread scheduling algorith

recycled by GC.10, using Java to generate a random number of integers within a range(1422 likes)I tried to generate a random integer using Java, but was randomly assigned to a range. For example, the integer range is 5~10, which means that 5 is the smallest random value and 10 is the largest. A book from 5 to 10 can also be a generated random number.Solution SolutionsThe standard solution (before Java1.7) is as follows: 123456789 import java.util.random; public static int

follows:Importpublicstaticint randint (intint max) { Random Rand; int randomnum = Rand.nextint ((max-min) + 1) + min; return Randomnum;}Please check the relevant Javadoc. In practice,the Java.util.Random class is always better than java.lang.Math.random (). Especially when there is a direct API in the standard library to do this, there is no need to reinvent the wheel.Original link: Nolsit translation: Importnew.com-likenLink: http://www.importnew.com/16841.html[ Reprint please ke

faster. Like memcached it's often bound by available network or memory bandwidth instead of CPUs or other bottlenecks and would rar Ely was the culprit when your app was slowing down. The powerful data types is particularly important. They allow Redis to provide a fantastic GKFX queue (lists), a great messaging solution (pub/sub), a good place for s Toring sessions (hashes), and a compelling place for high score tracking (sorted sets). These is just a few examples that scratch the surface

Ju Long: Mars Agents! Today is Friday, what do you propose?Bejavagod: report Chrysanthemum long! I find it very interesting to save crooked nuts on StackOverflow!Pop haha, occasionally encountered problems will be used to StackOverflow, the above together with all kinds of great gods of various exquisite solutions, whether it is java,ios,android,js,.net, all kinds of problems have answers, of course, encoun

; Mark the rows in table instances as deleted (that ' s a "soft-delete")update instances set deleted_at = updated_at, deleted = id, power_state = 0, vm_state = "deleted", terminated_at = updated_at, root_device_name = NULL, task_state = NULL where deleted = 0; all your instances! Use show columns from instances; if you want to choose another column (s) for yourwhere-clause. Update the cache in table instance_info_chaches appropriatelyupdate instance_info_caches set deleted_at = updat

Let's first look at a question on StackOverflow, first on the code1 Public classpiece{2 Public Static voidmain (String [] args) {3Piece P2 =NewKnight ();4Knight P1 =NewKnight ();5 p1.capture (p2); 6 p2.capture (p1); 7 }8 Public voidcapture () {9System.out.println ("Capture");Ten } One Public voidcapture (Piece p) { ASystem.out.println ("I ' m bored"); - } - } the classKnightextendspiece{ - Public voidcapture (Piece p)

Go to segmentfault. comq100000004664570. If you have not solved the problem, go to stackoverflow to ask a question and register it. But you cannot find the question portal! Click askquestion To Tell Me howtoask... I didn't ask any questions at all... Tossing a problem, link: https://segmentfault.com/q/1010000004664570If you have not solved the problem yet, you can go to stackoverflow to ask a question and

From an issue on stackoverflow, we can see that Java Dynamic binding and stackoverflowjava Let's take a look at a problem on stackoverflow, first go to the code 1 public class Piece{ 2 public static void main (String [] args){ 3 Piece p2 = new Knight(); 4 Knight p1 = new Knight(); 5 p1.capture(p2); 6 p2.capture(p1); 7 } 8 public void capture(){ 9

Do not duplicate wheels. The most reliable method is Apache commons. IOUtilsJust a few lines of code. StringWriter writer = new StringWriter();IOUtils.copy(inputStream, writer, encoding);String theString = writer.toString();Or String theString = IOUtils.toString(inputStream, encoding) If you do not want to introduce the Apache library, you can do the same. static String convertStreamToString(java.io.InputStream is) { java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A"); retu

problemTo this day, I always thought: i + = j is equivalent to i = i + j; But suppose there is: int i = 5;long J = 8; i = i + j cannot compile, but i + = J can be compiled. This suggests that there is a difference between the two. Does this mean that i + = j, which is actually equivalent to i= (type of i) (i + j)?Essence Answer:This question, in fact, has been answered in the official documentation.please look here. §15.26.2 Compound Assignment Operators.And then copy the official documentation.

any actions * *) {return do_nothing;}}}Compare the following two copies of call instance 1. Redundancy: Each time an object is fetched, the emptyParserfactory. Getparser (); This would is an example of where null isn ' t (or shouldn ' t is) a valid response}= Parser. Findaction (Someinput) ; //Do nothing} else {action. dosomething ();} Streamline Parserfactory. Getparser (). Findaction (Someinput). dosomething (); Because no empty object is returned in any case, you can saf

The company uses VWG, Caslte ActiveRecord, Csla.net, quantz.net and other components as the basis for the company's development, since 2007, has been working normally, but recently (2015.12 months) since the opening of the MDAA project, VS always automatically After the crash (Crashed), auto-start, after debugging, only get "StackOverflow", Stack overflow.Know the problem, but always can not find the reason should be how to deal with: the way to try i