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  • How to decide on what hardware to deploy web application

    - by Yuval A
    Suppose you have a web application, no specific stack (Java/.NET/LAMP/Django/Rails, all good). How would you decide on which hardware to deploy it? What rules of thumb exist when determining how many machines you need? How would you formulate parameters such as concurrent users, simultaneous connections and DB read/write ratio to a decision on how much, and which, hardware you need? Any resources on this issue would be very helpful...

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  • How to shift pixels of a pixmap efficient in Qt4

    - by stanleyxu2005
    Hello, I have implemented a marquee text widget using Qt4. I painted the text content onto a pixmap first. And then paint a portion of this pixmap onto a paint device by calling painter.drawTiledPixmap(offsetX, offsetY, myPixmap) My Imagination is that, Qt will fill the whole marquee text rectangle with the content from myPixmap. Is there a ever faster way, to shift all existing content to left by 1px and than fill the newly exposed 1px wide and N-px high area with the content from myPixmap?

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  • Query to return internal details about stored function in MS-SQL database

    - by Anthony
    I have been given access to a ms-sql database that is currently used by 3rd party app. As such, I don't have any documentation on how that application stores the data or how it retrieves it. I can figure a few things out based on the names of various tables and the parameters that the user-defined functions takes and returns, but I'm still getting errors at every other turn. I was thinking that it would be really helpful if I could see what the stored functions were doing with the parameters given to return the output. Right now all I've been able to figure out is how to query for the input parameters and the output columns. Is there any built-in information_schema table that will expose what the function is doing between input and output?

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  • How often to run getWritableDatabase() and getReadableDatabase()?

    - by jawonlee
    I'm writing a Service, a Content Provider, and one or more apps. The Service writes new data to the Content Provider's SQLite database every 5 minutes or so plus at user input, and is intended to run pretty much forever in the background. The app, when running, will display data pulled from the Content Provider, and will be refreshed whenever the Service puts more data into the Content Provider's database. Given that the Service only inserts into the database once every five minutes, when is the right time to call SQLiteOpenHelper's getWritableDatabase() / getReadableDatabase()? Is it on the onCreate() of the Content Provider, or should I run it every time there is an insert() and close it at the end of insert()? The data being inserted every 5 minutes will contain multiple inserts.

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  • fastest way to crawl recursive ntfs directories in C++

    - by Peter Parker
    I have written a small crawler to scan and resort directory structures. It based on dirent(which is a small wrapper around FindNextFileA) In my first benchmarks it is surprisingy slow: around 123473ms for 4500 files(thinkpad t60p local samsung 320 GB 2.5" HD). 121481 files found in 123473 milliseconds Is this speed normal? This is my code: int testPrintDir(std::string strDir, std::string strPattern="*", bool recurse=true){ struct dirent *ent; DIR *dir; dir = opendir (strDir.c_str()); int retVal = 0; if (dir != NULL) { while ((ent = readdir (dir)) != NULL) { if (strcmp(ent->d_name, ".") !=0 && strcmp(ent->d_name, "..") !=0){ std::string strFullName = strDir +"\\"+std::string(ent->d_name); std::string strType = "N/A"; bool isDir = (ent->data.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) !=0; strType = (isDir)?"DIR":"FILE"; if ((!isDir)){ //printf ("%s <%s>\n", strFullName.c_str(),strType.c_str());//ent->d_name); retVal++; } if (isDir && recurse){ retVal += testPrintDir(strFullName, strPattern, recurse); } } } closedir (dir); return retVal; } else { /* could not open directory */ perror ("DIR NOT FOUND!"); return -1; } }

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  • Why the difference in speed?

    - by AngryHacker
    Consider this code: function Foo(ds as OtherDLL.BaseObj) dim lngRowIndex as long dim lngColIndex as long for lngRowIndex = 1 to ubound(ds.Data, 2) for lngColIndex = 1 to ds.Columns.Count Debug.Print ds.Data(lngRowIndex, lngColIndex) next next end function OK, a little context. Parameter ds is of type OtherDLL.BaseObj which is defined in a referenced ActiveX DLL. ds.Data is a variant 2-dimensional array (one dimension carries the data, the other one carries the column index. ds.Columns is a Collection of columns in 'ds.Data`. Assuming there are at least 400 rows of data and 25 columns, this code takes about 15 seconds to run on my machine. Kind of unbelievable. However if I copy the variant array to a local variable, so: function Foo(ds as OtherDLL.BaseObj) dim lngRowIndex as long dim lngColIndex as long dim v as variant v = ds.Data for lngRowIndex = 1 to ubound(v, 2) for lngColIndex = 1 to ds.Columns.Count Debug.Print v(lngRowIndex, lngColIndex) next next end function the entire thing processes in barely any noticeable time (basically close to 0). Why?

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  • Scalability of Ruby on Rails versus PHP

    - by Daniel
    Can anyone comment on which is more scalable between RoR and PHP? I have heard that RoR is less scalable than PHP since RoR has a little more overhead with its MVC framework while PHP is more low level and lighter. This is a bit vague - can anyone explain better?

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  • Pros and Cons of using SqlCommand Prepare in C#?

    - by MadBoy
    When i was reading books to learn C# (might be some old Visual Studio 2005 books) I've encountered advice to always use SqlCommand.Prepare everytime I execute SQL call (whether its' a SELECT/UPDATE or INSERT on SQL SERVER 2005/2008) and I pass parameters to it. But is it really so? Should it be done every time? Or just sometimes? Does it matter whether it's one parameter being passed or five or twenty? What boost should it give if any? Would it be noticeable at all (I've been using SqlCommand.Prepare here and skipped it there and never had any problems or noticeable differences). For the sake of the question this is my usual code that I use, but this is more of a general question. public static decimal pobierzBenchmarkKolejny(string varPortfelID, DateTime data, decimal varBenchmarkPoprzedni, decimal varStopaOdniesienia) { const string preparedCommand = @"SELECT [dbo].[ufn_BenchmarkKolejny](@varPortfelID, @data, @varBenchmarkPoprzedni, @varStopaOdniesienia) AS 'Benchmark'"; using (var varConnection = Locale.sqlConnectOneTime(Locale.sqlDataConnectionDetailsDZP)) //if (varConnection != null) { using (var sqlQuery = new SqlCommand(preparedCommand, varConnection)) { sqlQuery.Prepare(); sqlQuery.Parameters.AddWithValue("@varPortfelID", varPortfelID); sqlQuery.Parameters.AddWithValue("@varStopaOdniesienia", varStopaOdniesienia); sqlQuery.Parameters.AddWithValue("@data", data); sqlQuery.Parameters.AddWithValue("@varBenchmarkPoprzedni", varBenchmarkPoprzedni); using (var sqlQueryResult = sqlQuery.ExecuteReader()) if (sqlQueryResult != null) { while (sqlQueryResult.Read()) { //sqlQueryResult["Benchmark"]; } } } }

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  • how do i connect to MSSQL 2008 database in JAVA with jbbc

    - by shuxer
    Hello I have MSSQL 2008 installed on my local PC, and my java application needs to connect to a mssql database. I am a new to MSSQL and i would like get some help on creating user login for my java application and getting connection via jdbc. So far i tried to create a user login for my app and used following connection string, but i doest work at all. Any help and hint will be appreciated. jdbc:jtds:sqlserver://127.0.0.1:1433/dotcms username="shuxer" password="itarator" Thanks in advance.

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  • WCF high instance count: anyone knows negative sideffects?

    - by Alex
    Hi there! Did anyone experience or know of negative side effects from having a high service instance count like 60k? Aside from the memory consumption of course. I am planning to increase the threshold for the maximum allowed instance count in our production environments. I am basically sick of severe production incidents just because "something" forgot to close a proxy properly. I plan to go to something like 60k instances which will allow the service to survive using default session timeouts at a call rate average for our clients. Thanks, Alex

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  • Avoid having a huge collection of ids by calling a DAO.getAll()

    - by Michael Bavin
    Instead of returning a List<Long> of ids when calling PersonDao.getAll() we wanted not to have an entire collection of ids in memory. Seems like returning a org.springframework.jdbc.support.rowset.SqlRowSet and iterate over this rowset would not hold every object in memory. The only problem here is i cannot cast this row to my entity. Is there a better way for this?

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  • Know of any Java garbage collection log analysis tools?

    - by braveterry
    I'm looking for a tool or a script that will take the console log from my web app, parse out the garbage collection information and display it in a meaningful way. I'm starting up on a Sun Java 1.4.2 JVM with the following flags: -verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails The log output looks like this: 54.736: [Full GC 54.737: [Tenured: 172798K->18092K(174784K), 2.3792658 secs] 257598K->18092K(259584K), [Perm : 20476K->20476K(20480K)], 2.4715398 secs] Making sense of a few hundred of these kinds of log entries would be much easier if I had a tool that would visually graph garbage collection trends.

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  • Does the order of columns matter in a group by clause?

    - by Jeff Meatball Yang
    If I have two columns, one with very high cardinality and one with very low cardinality (unique # of values), does it matter in which order I group by? Here's an example: select dimensionName, dimensionCategory, sum(someFact) from SomeFact f join SomeDim d on f.dimensionKey = d.dimensionKey group by d.dimensionName, -- large number of unique values d.dimensionCategory -- small number of unique values Are there situations where it matters?

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  • error in mysql syntax in vb.net

    - by user225269
    I get this error, while I'm testing the code below: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[student](ID, LASTNAME, FIRSTNAME, SCHOOL) VALUES ('333', 'aaa', 'aaa', 'aaa')' at line 1 I just recycled the code that I used in manipulating ms sql database. So the syntax must be wrong. What might be the correct syntax for adding records into mysql database? Here is my current code: idnum = TextBox1.Text lname = TextBox2.Text fname = TextBox3.Text skul = TextBox4.Text Using sqlcon As New MySqlConnection("Server=localhost; Database=testing;Uid=root;Pwd=nitoryolai123$%^;") sqlcon.Open() Dim sqlcom As New MySqlCommand() sqlcom.Connection = sqlcon sqlcom.CommandText = "INSERT INTO [student](ID, LASTNAME, FIRSTNAME, SCHOOL) VALUES (@ParameterID, @ParameterLastName, @ParameterFirstName, @ParameterSchool)" sqlcom.Parameters.AddWithValue("@ParameterID", TextBox1.Text) sqlcom.Parameters.AddWithValue("@ParameterLastName", TextBox2.Text) sqlcom.Parameters.AddWithValue("@ParameterFirstName", TextBox3.Text) sqlcom.Parameters.AddWithValue("@ParameterSchool", TextBox4.Text) sqlcom.ExecuteNonQuery() End Using Please help, thanks

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  • NHibernate unintentional lazy property loading

    - by chiccodoro
    I introduced a mapping for a business object which has (among others) a property called "Name": public class Foo : BusinessObjectBase { ... public virtual string Name { get; set; } } For some reason, when I fetch "Foo" objects, NHibernate seems to apply lazy property loading (for simple properties, not associations): The following code piece generates n+1 SQL statements, whereof the first only fetches the ids, and the remaining n fetch the Name for each record: ISession session = ...IQuery query = session.CreateQuery(queryString); ITransaction tx = session.BeginTransaction(); List<Foo> result = new List<Foo>(); foreach (Foo foo in query.Enumerable()) { result.Add(foo); } tx.Commit(); session.Close(); produces: NHibernate: select foo0_.FOO_ID as col_0_0_ from V1_FOO foo0_<br/> NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 81<br/> NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36470<br/> NHibernate: SELECT foo0_.FOO_ID as FOO1_2_0_, foo0_.NAME as NAME2_0_ FROM V1_FOO foo0_ WHERE foo0_.FOO_ID=:p0;:p0 = 36473 Similarly, the following code leads to a LazyLoadingException after session is closed: ISession session = ... ITransaction tx = session.BeginTransaction(); Foo result = session.Load<Foo>(id); tx.Commit(); session.Close(); Console.WriteLine(result.Name); Following this post, "lazy properties ... is rarely an important feature to enable ... (and) in Hibernate 3, is disabled by default." So what am I doing wrong? I managed to work around the LazyLoadingException by doing a NHibernateUtil.Initialize(foo) but the even worse part are the n+1 sql statements which bring my application to its knees. This is how the mapping looks like: <class name="Foo" table="V1_FOO"> ... <property name="Name" column="NAME"/> </class> BTW: The abstract "BusinessObjectBase" base class encapsulates the ID property which serves as the internal identifier.

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  • Is there a way to rewrite the SQL query efficiently

    - by user320587
    hi, I have two tables with following definition TableA TableB ID1 ID2 ID3 Value1 Value ID1 Value1 C1 P1 S1 S1 C1 P1 S2 S2 C1 P1 S3 S3 C1 P1 S5 S4 S5 The values are just examples in the table. TableA has a clustered primary key ID1, ID2 & ID3 and TableB has p.k. ID1 I need to create a table that has the missing records in TableA based on TableB The select query I am trying to create should give the following output C1 P1 S4 To do this, I have the following SQL query SELECT DISTINCT TableA.ID1, TableA.ID2, TableB.ID1 FROM TableA a, TableB b WHERE TableB.ID1 NOT IN ( SELECT DISTINCT [ID3] FROM TableA aa WHERE a.ID1 == aa.ID1 AND a.ID2 == aa.ID2 ) Though this query works, it performs poorly and my final TableA may have upto 1M records. is there a way to rewrite this more efficiently. Thanks for any help, Javid

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  • How to control the memory size of continuously running windows service?

    - by Snowill
    Hi, I have created a windows service which is continuously polling a database. For this purpose i have a timer in place. Ever time i am querying a database table i open a connection and close it immediately after my work is done. Right now i am doing this every 20 seconds for testing purpose, but later this time might increase to 5 - 10 minutes. What happens is everytime the database table is polled there is an increase of 10-12 KB in the size of the memory of the service running. This i can see in the task manager. Is there any way to control this.

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  • MySQL Locking Up

    - by Ian
    I've got a innodb table that gets a lot of reads and almost no writes (like, 1 write for every 400,000 reads approx). I'm running into a pretty big problem though when I do INSERT into the table. MySQL completely locks up. It uses 100% cpu, and every single other table (in other databases even) have their statuses set to "Locked" until the INSERT is done. This is a big problem because MySQL stays locked up for up to 4 minutes. I'm using version 5.1.47 (rpm from mysql.com). Any ideas?

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  • Speeding up jQuery empty() or replaceWith() Functions When Dealing with Large DOM Elements

    - by Levi Hackwith
    Let me start off by apologizing for not giving a code snippet. The project I'm working on is proprietary and I'm afraid I can't show exactly what I'm working on. However, I'll do my best to be descriptive. Here's a breakdown of what goes on in my application: User clicks a button Server retrieves a list of images in the form of a data-table Each row in the table contains 8 data-cells that in turn each contain one hyperlink Each request by the user can contain up to 50 rows (I can change this number if need be) That means the table contains upwards of 800 individual DOM elements My analysis shows that jQuery("#dataTable").empty() and jQuery("#dataTable).replaceWith(tableCloneObject) take up 97% of my overall processing time and take on average 4 - 6 seconds to complete. I'm looking for a way to speed up either of the above mentioned jQuery functions when dealing with massive DOM elements that need to be removed / replaced. I hope my explanation helps.

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  • Sql query: use where in or foreach?

    - by phenevo
    Hi, I'm using query, where the piece is: ...where code in ('va1','var2'...') I have about 50k of this codes. It was working when I has 30k codes, but know I get: The query processor ran out of internal resources and could not produce a query plan. This is a rare event and only expected for extremely complex queries or queries that reference a very large number of tables or partition I think that problem is related with IN... So now I'm planning use foreach(string code in codes) ...where code =code Is it good Idea ??

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  • Difficulty determining the file type of text database file

    - by Joseph Silvashy
    So the USDA has some weird database of general nutrition facts about food, and well naturally we're going to steal it for use in our app. But anyhow the format of the lines is like the following: ~01001~^~0100~^~Butter, salted~^~BUTTER,WITH SALT~^~~^~~^~Y~^~~^0^~~^6.38^4.27^8.79^3.87 ~01002~^~0100~^~Butter, whipped, with salt~^~BUTTER,WHIPPED,WITH SALT~^~~^~~^~Y~^~~^0^~~^6.38^4.27^8.79^3.87 ~01003~^~0100~^~Butter oil, anhydrous~^~BUTTER OIL,ANHYDROUS~^~~^~~^~Y~^~~^0^~~^6.38^4.27^8.79^3.87 ~01004~^~0100~^~Cheese, blue~^~CHEESE,BLUE~^~~^~~^~Y~^~~^0^~~^6.38^4.27^8.79^3.87 With those odd ~ and ^ separating the values, It also lacks a header row but thats ok, I can figure that out from the other stuff on their site: http://www.ars.usda.gov/Services/docs.htm?docid=8964 Any help would be great! If it matters we're making an open/free API with Ruby to query this data. Additionally I'm having a tough time posing this question so I've made it a community wiki so we can all pitch in!

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  • database logic for tracking each and every operation in my web application

    - by ripa
    I am developing an Web application. In my application, I need to keep track of each and every operation for every logged in user. I have planned following for achieving this task:- I will create stored procedure in mysql. I will trigger this procedure on each table's insert , update delete. This is an tough job for me. Will anybody direct me in the right way? I am using PHP based Codeigniter framework and mysql database.

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  • any faster alternative??

    - by kaushik
    I have to read a file from a particular line number and i know the line number say "n": i have been thinking of two choice: 1)for i in range(n) fname.readline() k=readline() print k 2)i=0 for line in fname: dictionary[i]=line i=i+1 but i want to know faster alternative as i might have to perform this on different files 20000 times. is there is any other better alternatives?? thanking u

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