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  • Query multiple currencies

    - by TiuTalk
    I need store multiple currencies on my database... Here's the problem: Example Tables: [ Products ] id (INT, PK) name (VARCHAR) price (DECIMAL) currency (INT, FK) [ Currencies ] id (INT, PK) name (VARCHAR) conversion (DECIMAL) # To U$ I'll store the product price with the currency selected by the user... Later I need to search the products using a price interval like "Search products with price from U$ 50 to U$ 100" and I need the system convert these values "on the fly" to run the SQL Query and filter the products. And I really don't know how to make this query... :/

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  • .net Compiler Optimizations

    - by Dested
    I am writing an application that I need to run at incredibly low speeds. The application creates and destroys memory in creative ways throughout its run, and it works just fine. I am wondering what compiler optimizations occur so I can try to build to that. One trick off hand is that the CLR handles arrays much faster than lists, so if you need to handle a ton of elements in a List, you may be better off calling ToArray() and handling it rather than calling ElementAt() again and again. I am wondering if there is any sort of comprehensive list for this kind of thing, or maybe the SO community can create one :-)

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  • Optimize Binary Search Algorithm

    - by Ganesh M
    In a binary search, we have two comparisons one for greater than and other for less than, otherwise its the mid value. How would you optimize so that we need to check only once? bool binSearch(int array[], int key, int left, int right) { mid = left + (right-left)/2; if (key < array[mid]) return binSearch(array, key, left, mid-1); else if (key > array[mid]) return binSearch(array, key, mid+1, right); else if (key == array[mid]) return TRUE; // Found return FALSE; // Not Found }

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  • Common causes of slow performing jQuery and how to optimize the code?

    - by Polaris878
    Hello, This might be a bit of a vague or general question, but I figure it might be able to serve as a good resource for other jQuery-ers. I'm interested in common causes of slow running jQuery and how to optimize these cases. We have a good amount of jQuery/JavaScript performing actions on our page... and performance can really suffer with a large number off elements. What are some obvious performance pitfalls you know of with jQuery? What are some general optimizations a jQuery-er can do to squeeze every last bit of performance out of his/her scripts? One example: a developer may use a selector to access an element that is slower than some other way. Thanks

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  • Adding a Third Table to a Two-Table Join Query

    - by John
    Hello, The query below works just fine. It pulls fields from two MySQL tables, "comment" and "login". It does this for rows where "username" in the table "login" equals the variable "$profile." It also pulls fields for rows where "loginid" in the table "comment" equals the "loginid" that is also being pulled from "login." I would like to pull data from a third table called "submission," which has the following fields: submissionid loginid title url displayurl datesubmitted I would like to pull fields from rows in "submission" where "loginid" equals the "loginid" that is already being pulled from the other two tables, "login" and "comment." How can I do this? Thanks in advance, John Query: $sqlStrc = "SELECT l.username, l.loginid, c.loginid, c.commentid, c.submissionid, c.comment, c.datecommented FROM comment AS c INNER JOIN login AS l ON c.loginid = l.loginid WHERE l.username = '$profile' ORDER BY c.datecommented DESC LIMIT 10";

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  • In ArrayBlockingQueue, why copy final member field into local final variable?

    - by mjlee
    In ArrayBlockingQueue, any method that requires lock will get set 'final' local variable before calling 'lock()'. public boolean offer(E e) { if (e == null) throw new NullPointerException(); final ReentrantLock lock = this.lock; lock.lock(); try { if (count == items.length) return false; else { insert(e); return true; } } finally { lock.unlock(); } } Is there any reason to set a local variable 'lock' from 'this.lock' when field 'this.lock' is final also. Additionally, it also set local variable of E[] before acting on. private E extract() { final E[] items = this.items; E x = items[takeIndex]; items[takeIndex] = null; takeIndex = inc(takeIndex); --count; notFull.signal(); return x; } Is there any reason for copying to local final variable?

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  • Command Query Separation validating for retries

    - by Neil Barnwell
    So I'm comfortable with the basic concept of CQS, where you might have a command that writes to one database, and that updates the query database that you read from. However, consider the scenario where you are entering data, and want to prevent duplicates. Using new employee data entry an employee register as an example, working through a pile of application forms to key in the new employees' details: Take top sheet. Key in employee name and unique payroll number to UI. Submit. Put paper in "completed pile". Repeat. How would you now prevent the user from keying in the same payroll number again, say for instance if they get distracted and can't remember whether they've keyed one in already and the "message" hasn't got all the way back to the query db for the user to search?

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  • Write file need to optimised for heavy traffic part 2

    - by Clayton Leung
    For anyone interest to see where I come from you can refer to part 1, but it is not necessary. write file need to optimised for heavy traffic Below is a snippet of code I have written to capture some financial tick data from the broker API. The code will run without error. I need to optimize the code, because in peak hours the zf_TickEvent method will be call more than 10000 times a second. I use a memorystream to hold the data until it reaches a certain size, then I output it into a text file. The broker API is only single threaded. void zf_TickEvent(object sender, ZenFire.TickEventArgs e) { outputString = string.Format("{0},{1},{2},{3},{4}\r\n", e.TimeStamp.ToString(timeFmt), e.Product.ToString(), Enum.GetName(typeof(ZenFire.TickType), e.Type), e.Price, e.Volume); fillBuffer(outputString); } public class memoryStreamClass { public static MemoryStream ms = new MemoryStream(); } void fillBuffer(string outputString) { byte[] outputByte = Encoding.ASCII.GetBytes(outputString); memoryStreamClass.ms.Write(outputByte, 0, outputByte.Length); if (memoryStreamClass.ms.Length > 8192) { emptyBuffer(memoryStreamClass.ms); memoryStreamClass.ms.SetLength(0); memoryStreamClass.ms.Position = 0; } } void emptyBuffer(MemoryStream ms) { FileStream outStream = new FileStream("c:\\test.txt", FileMode.Append); ms.WriteTo(outStream); outStream.Flush(); outStream.Close(); } Question: Any suggestion to make this even faster? I will try to vary the buffer length but in terms of code structure, is this (almost) the fastest? When memorystream is filled up and I am emptying it to the file, what would happen to the new data coming in? Do I need to implement a second buffer to hold that data while I am emptying my first buffer? Or is c# smart enough to figure it out? Thanks for any advice

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  • MD5 and Hibernate Query

    - by theJava
    public Login authenticate(Login login) { String query = "SELECT L FROM Login AS L WHERE L.email=? AND L.password=?"; Object[] parameters = { login.getEmail(), login.getPassword() }; List<Login> resultsList = (getHibernateTemplate().find(query,parameters)); if (resultsList.isEmpty()) { //error dude } else if (resultsList.size() > 1) { //throw expections } else { Login login1 = (Login) resultsList.get(0); return login1; } return null; } I have my DB tables password col set as MD5, now how to retrieve it back here.

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  • How to optimize this javascript code?

    - by Andrija
    I have a jsp which uses a lot of javascript and it's just not fast enough. I would like to optimize it so first, here's a part of the code: In the jsp I have the initialization: window.onload = function () { formCollection.pageSize.value = "<%= pagingSize%>"; elemCollection = iDom3.Table.all["spis"].XML.DOM; <% if (resultList != null) { %> elementsNumber = <%= resultList.size() %>; <%} else { %> elementsNumber = 0; <% } %> contextPath = "<%= request.getContextPath() %>"; } In my js file I have two types of js functions: // gets the first element and sets it's value to all the other; //the selectSingleNode function is used because I use XSLT transformation //to generate the table _setTehJed = function(){ var resultId = formCollection.elements["idTehJedinice_spis_1"].value; var resultText = formCollection.elements["tehnicka_spis_1"].value; if (resultId != ""){ var counter = 1; while (counter<elementsNumber){ counter++; if(formCollection.elements["idTehJedinice_spis_"+counter] != null){ formCollection.elements["idTehJedinice_spis_"+counter].value=resultId; formCollection.elements["tehnicka_spis_"+counter].value=resultText; } var node=elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'tehnicka']/title"); node.text=resultText; var node2=elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'idTehJedinice']/title"); node2.text=resultId; } } } // sets the elements checkbox to checked or unchecked _SelectCheckRokCuvanja = { all : [], Item : function (oItem, sId) { this.all["spis_"+sId] = oItem.value; if (oItem.checked) { elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "true"); }else{ elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "false"); } } } I've used these tips: http://blogs.msdn.com/b/ie/archive/2006/08/28/728654.aspx http://code.google.com/speed/articles/optimizing-javascript.html but I still think something could be done like defining the functions like this: In the jsp: window.onload = function () { iDom3.DigitalnaArhivaPrihvat.formCollection=document.forms["controller"]; iDom3.DigitalnaArhivaPrihvat.formCollection.pageSize.value = "<%= pagingSize%>"; iDom3.DigitalnaArhivaPrihvat.elemCollection = iDom3.Table.all["spis"].XML.DOM; <% if (resultList != null) { %> iDom3.DigitalnaArhivaPrihvat.elementsNumber = <%= resultList.size() %> <%} else { %> iDom3.DigitalnaArhivaPrihvat.elementsNumber = 0; <% } %> } in the js: iDom3.DigitalnaArhivaPrihvat = { formCollection:null, elemCollection:null, elementsNumber:null, _setTehJed : function(){ var resultId = this.formCollection.elements.idTehJedinice_spis_1.value; var resultText = this.formCollection.elements.tehnicka_spis_1.value; if (resultId != ""){ var counter = 1; while (counter<this.elementsNumber){ counter++; if(this.formCollection.elements["idTehJedinice_spis_"+counter] !== null){ this.formCollection.elements["idTehJedinice_spis_"+counter].value=resultId; this.formCollection.elements["tehnicka_spis_"+counter].value=resultText; } var node=this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'tehnicka']/title"); node.text=resultText; var node2=this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+counter+"']/data[@col = 'idTehJedinice']/title"); node2.text=resultId; } } }, _SelectCheckRokCuvanja = { all : [], Item : function (oItem, sId) { this.all["spis_"+sId] = oItem.value; if (oItem.checked) { this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "true"); }else{ this.elemCollection.selectSingleNode("/suite/table/rows/row[@id = 'spis_"+sId+"']/data[@col = 'rokCheck']").setAttribute("default", "false"); } } } but the problem is scoping (if I do it like this, the second function does not execute properly). Any suggestions?

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  • How can i optimize this recursive method

    - by Tirdyr
    Hi there. I'm trying to make a word puzzle game, and for that i'm using a recursive method to find all possible words in the given letters. The letters is in a 4x4 board. Like this: ABCD EFGH HIJK LMNO The recursive method is called inside this loop: for (int y = 0; y < width; y++) { for (int x = 0; x < height; x++) { myScabble.Search(letters, y, x, width, height, "", covered, t); } } letters is a 2D array of chars. y & x is ints that shows where in the board width & height is also int, that tells the dimensions of the board "" is the string we are trying to make (the word) covered is an array of bools, to check if we allready used that square. t is a List (wich contains all the words to check against). The recursive method that need optimizing: public void Search(char[,] letters, int y, int x, int width, int height, string build, bool[,] covered, List<aWord> tt) { // Dont get outside the bounds if (y >= width || y < 0 || x >= height || x < 0) { return; } // Dont deal with allrady covered squares if (covered[x, y]) { return; } // Get Letter char letter = letters[x, y]; // Append string pass = build + letter; // check if its a possibel word //List<aWord> t = myWords.aWord.Where(w => w.word.StartsWith(pass)).ToList(); List<aWord> t = tt.Where(w => w.word.StartsWith(pass)).ToList(); // check if the list is emphty if (t.Count < 10 && t.Count != 0) { //stop point } if (t.Count == 0) { return; } // Check if its a complete word. if (t[0].word == pass) { //check if its allrdy present in the _found dictinary if (!_found.ContainsKey(pass)) { //if not add the word to the dictionary _found.Add(pass, true); } } // Check to see if there is more than 1 more that matches string pass // ie. are there more words to find. if (t.Count > 1) { // make a copy of the covered array bool[,] cov = new bool[height, width]; for (int i = 0; i < width; i++) { for (int a = 0; a < height; a++) { cov[a, i] = covered[a, i]; } } // Set the current square as covered. cov[x, y] = true; // Continue in all 8 directions. Search(letters, y + 1, x, width, height, pass, cov, t); Search(letters, y, x + 1, width, height, pass, cov, t); Search(letters, y + 1, x + 1, width, height, pass, cov, t); Search(letters, y - 1, x, width, height, pass, cov, t); Search(letters, y, x - 1, width, height, pass, cov, t); Search(letters, y - 1, x - 1, width, height, pass, cov, t); Search(letters, y - 1, x + 1, width, height, pass, cov, t); Search(letters, y + 1, x - 1, width, height, pass, cov, t); } } The code works as i expected it to do, however it is very slow.. it takes about 2 mins to find the words. EDIT: i clarified that the letters array is 2D

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  • Initializing a C++ vector to random values... fast

    - by Flamewires
    Hey, id like to make this as fast as possible because it gets called A LOT in a program i'm writing, so is there any faster way to initialize a C++ vector to random values than: double range;//set to the range of a particular function i want to evaluate. std::vector<double> x(30, 0.0); for (int i=0;i<x.size();i++) { x.at(i) = (rand()/(double)RAND_MAX)*range; } EDIT:Fixed x's initializer.

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  • How much faster is a database running in RAM?

    - by orokusaki
    I"m looking to run PostgreSQL in RAM for performance enhancement. The database isn't more than 1GB and shouldn't ever grow to more than 5GB. Is it worth doing? Are there any benchmarks out there? Is it buggy? My second major concern is: How easy is it to back things up when it's running purely in RAM. Is this just like using RAM as tier 1 HD, or is it much more complicated?

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  • Simplyfing code with a lot of ifs

    - by user278618
    I have a method which based on the enum, and to be clear at start we have this situation: public void MyMetohd(Somestatus status) { if(status == Somestatus.Enum1) { DoA(); DoB(); DoC(); DoD(); DoE(); } if(status == Somestatus.Enum2) { DoA(); DoB(); DoC(); DoD(); } if(status == Somestatus.Enum3) { DoA(); DoB(); DoC(); } if(status == Somestatus.Enum4) { DoA(); DoB(); } if(status == Somestatus.Enum5) { DoA(); } } How would you optimize this kind of code ( it isn't mine)?

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  • Compiler reordering around mutex boundaries?

    - by shojtsy
    Suppose I have my own non-inline functions LockMutex and UnlockMutex, which are using some proper mutex - such as boost - inside. How will the compiler know not to reorder other operations with regard to calls to the LockMutex and UnlockMutex? It can not possibly know how will I implement these functions in some other compilation unit. void SomeClass::store(int i) { LockMutex(_m); _field = i; // could the compiler move this around? UnlockMutex(_m); } ps: One is supposed to use instances of classes for holding locks to guarantee unlocking. I have left this out to simplify the example.

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  • Can I optimize this at all?

    - by Moshe
    I'm working on an iOS app and I'm using the following code for one of my tables to return the number of rows in a particular section: return [[kSettings arrayForKey:@"views"] count]; Is there any other way to write that line of code so that it is more memory efficient? EDIT: kSettings = NSUserDefaults standardUserDefaults. Is there any way to rewrite my line of code so that whatever memory it occupies is released sooner than it is released now?

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  • SQL query to select distinct record with 2 or more repetition in another field

    - by kyohiros
    So I have this table of book orders, it contains 2 columns, one is the order ID(primary key) and another is the ID of the book that the customer ordered. For example: | OrderID | BookID | | 0001 | B002 | | 0002 | B005 | | 0003 | B002 | | 0004 | B003 | | 0005 | B005 | | 0006 | B002 | | 0007 | B002 | What I want is to get the IDs of the books that got 2 or more purchases/orders, for example if I run the SQL query against the above data, I would get this as the result: | BookID | | B002 | | B005 | I don't know if this can be archived in SQL or I have to built a simpler statement and repetitive run the query against all the records in another language. I need some help and thanks for reading my question.

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  • how can i substitute a NULL value for a 0 in an SQL Query result

    - by Name.IsNullOrEmpty
    SELECT EmployeeMaster.EmpNo, Sum(LeaveApplications.LeaveDaysTaken) AS LeaveDays FROM EmployeeMaster FULL OUTER JOIN LeaveApplications ON EmployeeMaster.id = LeaveApplications.EmployeeRecordID INNER JOIN LeaveMaster ON EmployeeMaster.id = LeaveMaster.EmpRecordID GRoup BY EmployeeMaster.EmpNo order by LeaveDays Desc with the above query, if an employee has no leave application record in table LeaveApplications, then their Sum(LeaveApplications.LeaveDaysTaken) AS LeaveDays column returns NULL. What i would like to do is place a value of 0 (Zero) instead of NULL. I want to do this because i have a calculated column in the same query whose formular depends on the LeaveDays returned and when LeaveDays is NULL, the formular some how fails. Is there away i can put 0 for NULL such that that i can get my desired result.

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  • Compile Flex application without debug? Optimisation options for flex compiler?

    - by maoanz
    I have created a simple test application with the following code var i : int; for (i=0; i<3000000; i++){ trace(i); } When I run the application, it's very slow to load, which means the "trace" is running. I check the flash player by right-clicking, the debugger option is not enable. So I wonder if there is an option to put in compiler to exclude the trace. Otherwise, I have to remove manually all the trace in the program. Are there any other options of compiler to optimize the flex application in a maximum way? Thanks

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  • How can I store large amount of data from a database to XML (speed problem, part three)?

    - by Andrija
    After getting some responses, the current situation is that I'm using this tip: http://www.ibm.com/developerworks/xml/library/x-tipbigdoc5.html (Listing 1. Turning ResultSets into XML), and XMLWriter for Java from http://www.megginson.com/downloads/ . Basically, it reads date from the database and writes them to a file as characters, using column names to create opening and closing tags. While doing so, I need to make two changes to the input stream, namely to the dates and numbers. // Iterate over the set while (rs.next()) { w.startElement("row"); for (int i = 0; i < count; i++) { Object ob = rs.getObject(i + 1); if (rs.wasNull()) { ob = null; } String colName = meta.getColumnLabel(i + 1); if (ob != null ) { if (ob instanceof Timestamp) { w.dataElement(colName, Util.formatDate((Timestamp)ob, dateFormat)); } else if (ob instanceof BigDecimal){ w.dataElement(colName, Util.transformToHTML(new Integer(((BigDecimal)ob).intValue()))); } else { w.dataElement(colName, ob.toString()); } } else { w.emptyElement(colName); } } w.endElement("row"); } The SQL that gets the results has the to_number command (e.g. to_number(sif.ID) ID ) and the to_date command (e.g. TO_DATE (sif.datum_do, 'DD.MM.RRRR') datum_do). The problems are that the returning date is a timestamp, meaning I don't get 14.02.2010 but rather 14.02.2010 00:00:000 so I have to format it to the dd.mm.yyyy format. The second problem are the numbers; for some reason, they are in database as varchar2 and can have leading zeroes that need to be stripped; I'm guessing I could do that in my SQL with the trim function so the Util.transformToHTML is unnecessary (for clarification, here's the method): public static String transformToHTML(Integer number) { String result = ""; try { result = number.toString(); } catch (Exception e) {} return result; } What I'd like to know is a) Can I get the date in the format I want and skip additional processing thus shortening the processing time? b) Is there a better way to do this? We're talking about XML files that are in the 50 MB - 250 MB filesize category.

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  • Controlling read and write access width to memory mapped registers in C

    - by srking
    I'm using and x86 based core to manipulate a 32-bit memory mapped register. My hardware behaves correctly only if the CPU generates 32-bit wide reads and writes to this register. The register is aligned on a 32-bit address and is not addressable at byte granularity. What can I do to guarantee that my C (or C99) compiler will only generate full 32-bit wide reads and writes in all cases? For example, if I do a read-modify-write operation like this: volatile uint32_t* p_reg = 0xCAFE0000; *p_reg |= 0x01; I don't want the compiler to get smart about the fact that only the bottom byte changes and generate 8-bit wide read/writes. Since the machine code is often more dense for 8-bit operations on x86, I'm afraid of unwanted optimizations. Disabling optimizations in general is not an option.

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  • Optimizing a "set in a string list" to a "set as a matrix" operation

    - by Eric Fournier
    I have a set of strings which contain space-separated elements. I want to build a matrix which will tell me which elements were part of which strings. For example: "" "A B C" "D" "B D" Should give something like: A B C D 1 2 1 1 1 3 1 4 1 1 Now I've got a solution, but it runs slow as molasse, and I've run out of ideas on how to make it faster: reverseIn <- function(vector, value) { return(value %in% vector) } buildCategoryMatrix <- function(valueVector) { allClasses <- c() for(classVec in unique(valueVector)) { allClasses <- unique(c(allClasses, strsplit(classVec, " ", fixed=TRUE)[[1]])) } resMatrix <- matrix(ncol=0, nrow=length(valueVector)) splitValues <- strsplit(valueVector, " ", fixed=TRUE) for(cat in allClasses) { if(cat=="") { catIsPart <- (valueVector == "") } else { catIsPart <- sapply(splitValues, reverseIn, cat) } resMatrix <- cbind(resMatrix, catIsPart) } colnames(resMatrix) <- allClasses return(resMatrix) } Profiling the function gives me this: $by.self self.time self.pct total.time total.pct "match" 31.20 34.74 31.24 34.79 "FUN" 30.26 33.70 74.30 82.74 "lapply" 13.56 15.10 87.86 97.84 "%in%" 12.92 14.39 44.10 49.11 So my actual questions would be: - Where are the 33% spent in "FUN" coming from? - Would there be any way to speed up the %in% call? I tried turning the strings into factors prior to going into the loop so that I'd be matching numbers instead of strings, but that actually makes R crash. I've also tried going for partial matrix assignment (IE, resMatrix[i,x] <- 1) where i is the number of the string and x is the vector of factors. No dice there either, as it seems to keep on running infinitely.

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  • CouchDB Lucene How to URL Encode Query containing Minus (-)

    - by Peter
    I'd like to query text containing a minus (-) Sign, e.g. foo-bar with a couchdb lucene fulltext query. Following lucene rules I'd have to escape the minus, resulting in foo\-bar Last I'd have to urlencode the backslash resulting in foo%5C-bar So the complete url would be: http://127.0.0.1:5984/_fti/local/db/_design/foo/by_subject?q=foo%5C-bar Neither works. The result is always split in two phrases "q":"default:foo default:bar" Leading to documents containing only foo or bar being found also. Thanks for your help!

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  • How can I improve the below query?

    - by Newbie
    I have the following input. INPUT: TableA ID Sentences --- ---------- 1 I am a student 2 Have a nice time guys! What I need to do is to extract the words from the sentence(s) and insert each individual word in another table OUTPUT: SentenceID WordOccurance Word ---------- ------------ ----- 1 1 I 1 2 am 1 3 a 1 4 student 2 1 Have 2 2 a 2 3 nice 2 4 time 2 5 guys! I was able to get the answer by using the below query ;With numCTE As ( Select rn = 1 Union all Select rn+1 from numCTE where rn<1000) select SentenceID=id, WordOccurance=row_number()over(partition by TableA.ID order by rn), Word = substring(' '+sentences+' ', rn+1, charindex(' ',' '+sentences+' ', rn+1)-rn-1) from TableA join numCTE on rn <= len(' '+sentences+' ') where substring(' '+sentences+' ', rn,1) = ' ' order by id, rn How can I improve this query of mine.? Basically I am looking for a better solution than the one presented Thanks

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