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• MEMORY(HEAP) vs. InnoDB in a Read and Write Environment

  - by Johannes

  I want to program a real-time application using MySQL. It needs a small table (less than 10000 rows) that will be under heavy read (scan) and write (update and some insert/delete) load. I am really speaking of 10000 updates or selects per second. These statements will be executed on only a few (less than 10) open mysql connections. The table is small and does not contain any data that needs to be stored on disk. So I ask which is faster: InnoDB or MEMORY (HEAP)? My thoughts are: Both engines will probably serve SELECTs directly from memory, as even InnoDB will cache the whole table. What about the UPDATEs? (innodb_flush_log_at_trx_commit?) My main concern is the locking behavior: InnoDB row lock vs. MEMORY table lock. Will this present the bottleneck in the MEMORY implementation? Thanks for your thoughts!

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• How to call constructor of the current class and parent class at the same time?

  - by Siegfried

  public class A{ public A(int a, int b) {...} } public class B : A{ List a; List b; public B(){...} //constructor1 public B(int a, int b) : base(a,b){...} //constructor2 } My question is I need to initialize both list a and b in class B. If I put them in the constructor1, how can I call constructor1 in constructor2? I don't want to rewrite the initialization statements in constructor2 again. Thanks!

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• Sharing some info with all DLLs pulled into a process

  - by JBRWilkinson

  Hi all, We've got an Enterprise system which has many processes (EXEs, services, DCOM servers, COM+ apps, ISAPI, MMC snapins) all of which make use of many COM components. We've recently seen failures in some of the customer deployments, but are finding it hard to troubleshoot the cause. In order to track down the problem, we've augmented the entire source with logging statements where errors occur. In order to identify which logs came from what processes, the C++ logging code (compiled into all components) uses the EXE name to name the log. This is good for some cases, but not all - COM+ apps, ISAPI and MMC snapins all have system EXE names and the logs end up interleaved. I saw this post about shared data sections which might help, but what I don't understand is who decides what goes in the shared section. Is there any way I can guarantee that a particular piece of code writes into the shared section before anyone else reads it? Or is there a better solution to this problem?

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• unknown column in where clause

  - by ranzy

  $result = mysql_query("SELECT * FROM Volunteers WHERE Volunteers.eventID = " . $var); $sql = mysql_query("SELECT * FROM Members WHERE Members.pid = " . $temp); I am also doing or die(mysql_error()) at the end of both statements if that matter. My problem is that the first statement executes perfectly but in that table I store an attribute called pid. So the second statement is supposed to take that and return the row where it equals that pid so I can get the name. I get an error that says unknown column in 'a2' in 'where clause' where a2 the pid attribute returned from the first statement. Thanks for any help!

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• Preview result of update/insert query without comitting changes to database in MySQL?

  - by Camsoft

  I am writing a script to import CSV files into existing tables within my database. I decided to do the insert/update operations myself using PHP and INSERT/UPDATE statements, and not use MySQL's LOAD INFILE command, I have good reasons for this. What I would like to do is emulate the insert/update operations and display the results to the user, and then give them the option of confirming that this is OK, and then committing the changes to the database. I'm using InnoDB database engine with support for transactions. Not sure if this helps but was thinking down the line of insert/update, query data, display to user, then either commit or rollback transaction? Any advise would be appreciated.

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• JavaScript - question regarding data structure

  - by orokusaki

  I'm trying to calculate somebody's bowel health based on a points system. I can edit the data structure, or logic in any way. I'm just trying to write a function and data structure to handle this ability. Pseudo calculator function: // Bowel health calculator var points = 0; If age is from 30 and 34: points += 1 If age is from 35 and 40: points += 2 If daily BMs is from 1 and 3: points -= 1 If daily BMs is from 4 and 6: points -= 2 return points; Pseudo data structure: var points_map = { age: { '30-34': 1, '35-40': 2 }, dbm: { '1-3': -1, '4-6': -2 } }; I have a full spreadsheet of data like this, and I am trying to write a DRY version of code and a DRY version of this data (ie, probably not a string for the '30-34', etc) in order to handle this sort of thing without a humongous number of switch statements.

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• phpmyadmin and the database

  - by Jonathan

  Not sure I fully understand what phpmyadmin does. I created a database in phpmyadmin, and would now like to start accessing the data in it from php. However I have no idea where the database is? Should I export in the phpmyadmin software? I tried that but it came up with a .sql file which can be opened in notepad and contains the SQL statements used to create the datbase and the one table inside. Basically that doesn't look like a database to me.

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• iphone app hangs in AppDelegate (?)

  - by d_CFO

  No nib/IB, so I've inserted "myAppDelegate" in main and deleted the reference to main.xib in info.plist. Debug continues nicely through all five tab controllers; they seem to have gotten properly loaded into the nav controller. In fact, control passes out of the last "}" in applicationDidFinishLaunching. But there was no (visible) response back at [window addSubview:[tabBarController view]]; and [window makeKeyAndVisible]; statements, much less to the loadView within the first tab (program execution never gets there). The last line is, UIApplication _performInitializationWithURL:sourceBundleID:]. I missed a step? I executed a step improperly?

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• Tool to automatically add tracing or instrumentation to an .NET app?

  - by Tony_Henrich

  I have a .NET app which runs once a day. Sometimes there's a logical error somewhere which occurs randomly. Is there a tool like Eqatec's Tracer which automatically injects instrumentation in the code and logs everything to a file? The issue with Eqatec's Tracer is that it opens a window on the machine and it doesn't seem to log. My issue rarely occurs and I need to keep all logs for a long time. I don't want to change the source code and add logging statements all over the place. I am aware of PostSharp & Logfaces.

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• How to enable reading non-ascii characters in Servlets

  - by Daziplqa

  How to make the servlet accept non-ascii (Arabian, chines, etc) characters passed from JSPs? I've tried to add the following to top of JSPs: <%@page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> And to add the following in each post/get method in the servlet: request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); I've tried to add a Filter that executes the above two statements instead of in the servlet. To be quite honest, these was working in the past, but now it doesn't work anymore. I am using tomcat 5.0.28/6.x.x on JDK1.6 on both Win & Linux boxes.

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• How do I get rid of extra lines in my output from Rails

  - by Dan B

  I am using Rails 2.1 to output tables from a database. But the output includes lots of extra lines and tabs. I am using a while loop with lots of nested if statements. I am also wrapping all of my non-output lines in <%- code -%. Any idea what might be happening and a solution? Thanks, ex: <tr> <td>Some data</td> <td>more data</td>

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• Java JPA @OneToMany neededs to reciprocate @ManyToOne?

  - by bguiz

  Create Table A ( ID varchar(8), Primary Key(ID) ); Create Table B ( ID varchar(8), A_ID varchar(8), Primary Key(ID), Foreign Key(A_ID) References A(ID) ); Given that I have created two tables using the SQL statements above, and I want to create Entity classes for them, for the class B, I have these member attributes: @Id @Column(name = "ID", nullable = false, length = 8) private String id; @JoinColumn(name = "A_ID", referencedColumnName = "ID", nullable = false) @ManyToOne(optional = false) private A AId; In class A, do I need to reciprocate the many-to-one relationship? @Id @Column(name = "ID", nullable = false, length = 8) private String id; @OneToMany(cascade = CascadeType.ALL, mappedBy = "AId") private List<B> BList; //<-- Is this attribute necessary? Is it a necessary or a good idea to have a reciprocal @OneToMany for the @ManyToOne? If I make the design decision to leave out the @OneToMany annotated attribute now, will come back to bite me further down.

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• Dynamic evaluation of a table column within an insert before trigger

  - by Tim Garver

  HI All, I have 3 tables, main, types and linked. main has an id column and 32 type columns. types has id, type linked has id, main_id, type_id I want to create an insert before trigger on the main table. It needs to compare its 32 type columns to the values in the types table if the main table column has an 'X' for its value and insert the main_id and types_id into the linked table. i have done a lot of searching, and it looks like a prepared statement would be the way to go, but i wanted to ask the experts. The issue, is i dont want to write 32 IF statements, and even if i did, i need to query the types table to get the ID for that type, seems like a huge waist of resources. Ideally i want to do this inside of my trigger: BEGIN DECLARE @types results_set -- (not sure if this is a valid type); -- (iam sure my loop syntax is all wrong here)... SET @types = (select * from types) for i=0;i<types.records;i++ { IF NEW.[i.type] = 'X' THEN insert into linked (main_id,type_id) values (new.ID, i.id); END IF; } END; Anyway, This is what i was hoping to do, maybe there is a way to dynamically set the field name inside of a results loop, but i cant find a good example of this. Thanks in advance Tim

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• Python continue from the point where exception was thrown

  - by James Lin

  Hi is there a way to continue from the point where exception was thrown? eg I have the following psudo code unique code 1 unique code 2 unique code 3 if I want to ignore the exceptions of any of the unique code statements I will have to do it like this: try: #unique code 1 except: pass try: #unique code 2 except: pass try: #unique code 3 except: pass but this isn't elegant to me, and for the life of me I can't remember how I resolved this kind of problem last time... what I want to have is something like try: unique code 1 unique code 2 unique code 3 except: continue from last exception raised

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• Best Practice to write Connection string for heavy traffic ASP.NET Web Application

  - by hungrycoder

  What is the best way to define connection string for a web application that has minimum 500 live users on the internet in terms of connection pooling. And load factors to consider? Suppose I have connection string as follows: initial catalog=Northwind; Min Pool Size=20;Max Pool Size=500; data source=localhost; Connection Timeout=30; Integrated security=sspi" as Max Pool Size is 500 and as live users exceed 500 say 520 will the remaining 20 users experience slower page load?? Or what if I have connection string as follows which doesn't talks anything about pooling or Connection time out? How the application behaves then? initial catalog=Northwind; data source=localhost; Integrated security=sspi" I'm using "Using statements" however to access the MYSQL database.

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• Foolproof way to check for nonzero (error) return code in windows batch file

  - by Pat

  Intro There's a lot of advice out there for dealing with return codes in batch files (using the ERROLEVEL mechanism), e.g. Get error code from within a batch file ERRORLEVEL inside IF Some of the advice is to do if errorlevel 1 goto somethingbad, while others recommend using the %ERRORLEVEL% variable and using ==, EQU, LSS, etc. There seem to be issues within IF statements and such, so then delayedexpansion is encouraged, but it seems to come with quirks of its own. Question What is a foolproof (i.e. robust, so it will work on nearly any system with nearly any return code) way to know if a bad (nonzero) code has been returned? My attempt For basic usage, the following seems to work ok to catch any nonzero return code: if not errorlevel 0 ( echo error level was nonzero )

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• Can ScalaCheck/Specs warnings safely be ignored when using SBT with ScalaTest?

  - by pdbartlett

  I have a simple FunSuite-based ScalaTest: package pdbartlett.hello_sbt import org.scalatest.FunSuite class SanityTest extends FunSuite { test("a simple test") { assert(true) } test("a very slightly more complicated test - purposely fails") { assert(42 === (6 * 9)) } } Which I'm running with the following SBT project config: import sbt._ class HelloSbtProject(info: ProjectInfo) extends DefaultProject(info) { // Dummy action, just to show config working OK. lazy val solveQ = task { println("42"); None } // Managed dependencies val scalatest = "org.scalatest" % "scalatest" % "1.0" % "test" } However, when I runsbt test I get the following warnings: ... [info] == test-compile == [info] Source analysis: 0 new/modified, 0 indirectly invalidated, 0 removed. [info] Compiling test sources... [info] Nothing to compile. [warn] Could not load superclass 'org.scalacheck.Properties' : java.lang.ClassNotFoundException: org.scalacheck.Properties [warn] Could not load superclass 'org.specs.Specification' : java.lang.ClassNotFoundException: org.specs.Specification [warn] Could not load superclass 'org.specs.Specification' : java.lang.ClassNotFoundException: org.specs.Specification [info] Post-analysis: 3 classes. [info] == test-compile == For the moment I'm assuming these are just "noise" (caused by the unified test interface?) and that I can safely ignore them. But it is slightly annoying to some inner OCD part of me (though not so annoying that I'm prepared to add dependencies for the other frameworks). Is this a correct assumption, or are there subtle errors in my test/config code? If it is safe to ignore, is there any other way to suppress these errors, or do people routinely include all three frameworks so they can pick and choose the best approach for different tests? TIA, Paul. (ADDED: scala v2.7.7 and sbt v0.7.4)

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• Can I avoid repeating myself in this situation (Java)

  - by UltimateGuy

  if (openFile == null) { new AppFileDialog().chooseFile("Save", appFrame); } if (openFile == null) { return; } Here I need to check to see if the user has already chosen a file. If not, they are given a prompt to. If the file is still null, the function returns without saving. The problem is the two identical if statements, can I avoid it? I take DRY very seriously, but at the same time KISS. Ideally the two go hand in hand, but in a situation like this, it seems they are mutually exclusive.

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• mysql LAST_INSERT_ID() used with multiple records INSERT statement

  - by bogdan

  Hello, If i insert multiple records with a loop that executes a single record insert, the last insert id returned is, as expected, the last one... but if i do a multiple records insert statement: INSERT INTO people (name,age) VALUES('William',25),('Bart',15),('Mary',12); let's say the three above are the first records inserted in the table...after the insert statement i expected last insert id to return 3, but it returned 1...the first insert id for the statement in question... So can someone please confirm if this is the normal behavior of LAST_INSERT_ID() in the context of multiple records INSERT statements...so i can base my code on it thanks :)

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• code-style: Is inline initialization of JS objects ok?

  - by michael

  I often find myself using inline initialization (see example below), especially in a switch statement when I don't know which case loop will hit. I find it easier to read than if statements. But is this good practice or will it incur side-effects or a performance hit? for (var i in array) { var o = o ? o : {}; // init object if it doesn't exist o[array[i]] = 1; // add key-values } Is there a good website to go to get coding style tips?

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• Using a class within another class in asp.net

  - by Phil

  In my site I have class A which selects the required page module (blog,content,gallery etc). I also have class B which provides sqlclient database objects and sql statements. If I use class B in a web form via "Imports Class B". I am able to access the contents. I now would like to use class B within class A but am struggling to find the correct syntax for importing it. Please can someone give me a basic example. We are coming from a classic asp background, and used to simply use includes. We are using VB Thanks.

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• Conditional Batch file renaming with mysql data

  - by Paul Stevens

  Hello, I wonder if anyone knows how could I rename multiple files, all of them originally named with same structure, and add some data extracted from a mysql DB according to specifics rules. For example I have 500 files named with this vars: ID NAME ADDRESS PHONE.wav = 1234567 PAULSIMON WESTDR122 9942213456.wav Now I need to rename files taking some data from the databases for each file, and append the data from a query appended to the filename. For example add the data resulting from a query Where some conditions match, and the data to build the query is taked from original file name, as ID or NAME. i other words, lets say that I want to build a query taking ID & NAME from file 1234567 PAULSIMON WESTDR123 9942213456.wav as WHERE statements to take another value as BirthDATE and add this to new filename, so final result should be: ID NAME ADDRESS PHONE BIRTHDATE.wav I will appreciate any help on this. I need this to be done on a LINUX server.

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• Errors/Warnings/Debug Info no longer appears in Debug Console

  - by Alex L

  Hi Guys: This one is driving me crazy. When I run my App and open the Debug Console there is nothing there! Nope, not even the output from my NSLog statements. Before I would see a bunch of debug information starting with [Session Started ...] and ending with 'Terminating in response to SpringBoard's termination'. The Status Bar at the bottom of the Console says my App was successfully launched. Even Errors and Warnings from my code no longer appear. How do I get this to show up again? Any help would be greatly appreciated.

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• Convert this VB code to C#?

  - by Róisín Kerr Lautman

  I was wondering if anyone would be able to help me convert the below code to c#? From what I have read it seems to be similar however I am not sure if my 'case' statements are still able to be used? Public Class Form1 Dim dteStart As Date Dim dteFinish As Date Dim span As TimeSpan Public Sub KeyDown(ByVal Sender As System.Object, ByVal e As _ System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown Select Case e.KeyCode Case Keys.Q Label1.BackColor = Color.Green dteStart = Now() Case Keys.W Label2.BackColor = Color.Green Case Keys.E Label3.BackColor = Color.Green Case Keys.R Label4.BackColor = Color.Green dteFinish = Now() span = dteFinish.Subtract(dteStart) Label5.Text = span.ToString End Select End Sub Public Sub KeyUp(ByVal Sender As System.Object, ByVal e As _ System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyUp Select Case e.KeyCode Case Keys.Q Label1.BackColor = Color.Red Case Keys.W Label2.BackColor = Color.Red Case Keys.E Label3.BackColor = Color.Red Case Keys.R Label4.BackColor = Color.Red End Select End Sub End Class

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• C variable decleration on gcc compiler - compile time error.

  - by liv2hak

  Assume the following C variable decleration int *A[10] , B[10][10]; Of the following expressions A[2] A[2][3] B[1] B[2][3] which will not give compile time errors if used as left hand sides of assignment statements in a C program. A) 1,2 and 4 only B) 2,3, and 4 only C) 2 and 4 only D) 4 only I have tried this on a gcc compiler.I assigned the value '0' to all the above variables.Only the third one showed an error.I can't really understand the reason.Can someone please expalin why that is.? Thanks

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