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• How to implement B+ Tree for file systems ?

  - by user312544

  I have a text file which contains some info on extents about all the files in the file system, like below C:\Program Files\abcd.txt 12345 100 23456 200 C:\Program Files\bcde.txt 56789 50 26746 300 ... Now i have another binary which tries to find out about extents for all the files. Now currently i am using linear search to find extent info for the files in the above mentioned text file. This is a time consuming process. Is there a better way of coding this ? Like Implementing any good data structure like BTree. If B+ Tree is used what is the key, branch factor i need to use ?

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• Database design efficiency with 1 to many relationships limited 1 to 3

  - by Joe

  This is in mysql, but its a database design issue. If you have a one to many relationship, like a bank customer to bank-accounts, typically you would have the table that records the bank-account information have a foreign key that keeps track of the relationship between account and customer. Now this follows the 3rd normal form thing and is a widely accepted way of doing it. Now lets say that you are going to limit a user to only having 3 accounts. The current database implementation will support this and nothing would need to change. But another way to do this would have 3 coloms in the account table that have the id of the 3 respective accounts in them. By the way this violates 1st normal form of db design. The question is what would be the advantage and disadvantages of having the user account relationship recored in this way over the traditional?

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• insert data into several tables

  - by csetzkorn

  Let us say I have a table (everything is very much simplified): create table OriginalData ( bla char(10) not null ) And I would like to insert its data (set based!) into two tables which model inheritance create table Statements ( Id int IDENTITY NOT NULL, ProposalDateTime DATETIME null ) create table Items ( StatementFk INT not null, ItemName NVARCHAR(255) null, primary key (StatementFk) ) Statements is the parent table and Items is the child table. I have no problem doing this with one row which involves the use of IDENT_CURRENT but I have no idea how to do this set based (i.e. enter several rows into both tables). Thanks. Best wishes, Christian

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• how to made one-to-one bidirectional relationships in grails?

  - by user369759

  I have two domain classes and want to have one-to-one BIDIRECTIONAL relation between them. I write: class Person { Book book; String name Integer age Date lastVisit static constraints = { book unique: true // "one-to-one". Without that = "Many-to-one". } } class Book { String title Date releaseDate String ISBN static belongsTo = [person:Person] // it makes relationship bi-directional regarding the grails-docs } So, i want to have bi-directional, i could NOT find link from Book to Person in generated SQL: CREATE TABLE `book` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `version` bigint(20) NOT NULL, `isbn` varchar(255) NOT NULL, `release_date` datetime NOT NULL, `title` varchar(255) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 So then it means it is not bidirectional then? How to make bidirectional?

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• How to capture the value change of numericUpDown ctrl real-time in .NET?

  - by Carlos_Liu

  I have implement the ValueChanged event, but I found it will be triggered only after change the focus from numericUpDown to other control or by clicking the up/down arrow. Inputting the value in the control will not trigger ValueChanged event. What I did now is adding an KeyDown event and judge if the input value is numeric (can not include SHIFT/CTRL/ALT key); but there is another case need to be involved: the user can paste value into the numericUpDown ctrl What I need is : When I was typing numeric value (only numeric) in the numericUpDown ctrl, it will known the content has been changed; When pasted a numeric value into the ctrl, it also kowns the content changed

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• What features of Scala cannot be translated to Java?

  - by Paul

  The Scala compiler compiles direct to Java byte code (or .NET CIL). Some of the features of Scala could be re-done in Java straightforwardly (e.g. simple for comprehensions, classes, translating anonymous/inner functionc etc). What are the features that cannot be translated that way? That is presumably mostly of academic interest. More usefully, perhaps, what are the key features or idioms of Scala that YOU use that cannot be easily represented in Java? Are there any the other way about? Things that can be done straightforwardly in Java that have no straightforward equivalent in Scala? Idioms in Java that don't translate?

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• How to recalculate primary index?

  - by JohnM2

  I have table in mysql database with autoincrement PRIMARY KEY. On regular basis rows in this table are being deleted an added. So the result is that value of PK of the latest row is growing very fast, but there is not so much rows in this table. What I want to do is to "recalculate" PK in this way, that the first row has PK = 1, second PK = 2 and so on. There are no external dependencies on PK of this table so it would be "safe". Is there anyway it can be done using only mysql queries/tools? Or I have to do it from my code?

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• JPA hibernate OneToOne mapping

  - by Stupidfrog

  enviroment: hibernate 4.1.6.final spring 3.1.2.release spring jpa 1.1.0.release postgresql 9.1-901-1.jdbc4 there is 2 table public A { private Long id; private Long name; } public B { private Long id; private Long table_a_id; } the A.id and B.id is sequential, unique , but no related.(means they are separately id for their own table). how to do mapping? i have tried some method, however the result is not i wanted, because it bind wrong. for example: public A { .... @OneToOne @JoinColumn(name = "id") private B table_b } public B { ... @JsonIgnore @OneToOne(mappedBy = "table_b") private A table_a; } when i query A the result is { "id":5, "table_b":{ "id":5, "table_a_id":4 } } obviously the data join by using their id but not joining using table_a_id. what i expect is { "id":4, "table_b":{ "id":5, "table_a_id":4 } } so can somebody teach me that, how to map this 2 table by using table b table_a_id(foregin key)

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• I need to add a KeyboardEvent to a movie clip in Flash cs4 AS 3.0

  - by psy-sci

  I have a movieclip called keyCButton that I want to add a keyboardEvent ("C" Key) to. This will play an animation from frames 2-30 with a sound. I have watched a few tutorials but still haven't gotten the correct information to make it work. The following is my code. stage.addEventListener(KeyboardEvent.KEY_DOWN, cNote); function cNote(event:KeyboardEvent):void { if (event.keyCode == Keyboard.SPACE) { keyCButton.gotoAndPlay(2) } } at frame 30 the code tells it to stop and then go back to frame 1 This works for the MouseEvent.CLICK but the KeyboardEvent does nothing.

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• How to strore Java Date to Mysql datetime...?

  - by user275843

  can any body tell me how can i store Java Date to Mysql datetime...? when i am trying to do so...only date is stored and time remain 00:00:00 in mysql date stores like this... 2009-09-22 00:00:00 i want not only date but also time...like 2009-09-22 08:08:11 please help me.... EDIT---- i am using JPA(Hibernate) with spring mydomain classes uses java.util.Date but i have created tables using handwritten queries... this is my create statement CREATE TABLE ContactUs (id BIGINT auto_increment, userName VARCHAR(30), email VARCHAR(50), subject VARCHAR(100), message VARCHAR(1024), messageType VARCHAR(15), contactUsTime datetime, primary key(id))TYPE=InnoDB;

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• Shortest command to calculate the sum of a column of output on Unix?

  - by Andrew

  I'm sure there is a quick and easy way to calculate the sum of a column of values on Unix systems (using something like awk or xargs perhaps), but writing a shell script to parse the rows line by line is the only thing that comes to mind at the moment. For example, what's the simplest way to modify the command below to compute and display the total for the SEGSZ column (70300)? ipcs -mb | head -6 IPC status from /dev/kmem as of Mon Nov 17 08:58:17 2008 T ID KEY MODE OWNER GROUP SEGSZ Shared Memory: m 0 0x411c322e --rw-rw-rw- root root 348 m 1 0x4e0c0002 --rw-rw-rw- root root 61760 m 2 0x412013f5 --rw-rw-rw- root root 8192

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• CDateTimeCtrl - preventing 'focus' change when setting date

  - by WalderFrey

  I'd like to use a CDateTimeCtrl to allow the user to select a non-weekend date. So, if the user increments the day (via a keypress) - and the resulting day is found to fall on a weekend - then the control should skip forward to the following Monday (don't let issues about month changes distract you, it's not relevant). Usually it's not a problem: when I handle the DTN_DATETIMECHANGE notification I can check the new date/time and if it's found to be a weekend then I can call SetTime on the control to update the date. However, if I set the style to DTS_SHOWNONE, this call to SetTime causes the control to shift the input 'focus' (term used loosely) to the 'none' checkbox, e.g. away from the day field. This prevents the user from using keyboard input to continue incrementing the date unless they subsequently use the right arrow key to reset the 'focus', which is just nasty. I would dearly like to prevent this focus shift from occurring. Is it even possible?

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• Why is Postgres doing a Hash in this query?

  - by Claudiu

  I have two tables: A and P. I want to get information out of all rows in A whose id is in a temporary table I created, tmp_ids. However, there is additional information about A in the P table, foo, and I want to get this info as well. I have the following query: SELECT A.H_id AS hid, A.id AS aid, P.foo, A.pos, A.size FROM tmp_ids, P, A WHERE tmp_ids.id = A.H_id AND P.id = A.P_id I noticed it going slowly, and when I asked Postgres to explain, I noticed that it combines tmp_ids with an index on A I created for H_id with a nested loop. However, it hashes all of P before doing a Hash join with the result of the first merge. P is quite large and I think this is what's taking all the time. Why would it create a hash there? P.id is P's primary key, and A.P_id has an index of its own.

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• SQL Server 2000, how to automate import data from excel

  - by Stan

  Say the source data comes in excel format, below is how I import the data. Converting to csv format via MS Excel Roughly find bad rows/columns by inspecting backup the table that needs to be updated in SQL Query Analyzer truncate the table (may need to drop foreign key constraint as well) import data from the revised csv file in SQL Server Enterprise Manager If there's an error like duplicate columns, I need to check the original csv and remove them I was wondering how to make this procedure more effecient in every step? I have some idea but not complete. For step 2&6, using scripts that can check automatically and print out all error row/column data. So it's easier to remove all errors once. For step 3&5, is there any way to automatically update the table without manually go through the importing steps? Could the community advise, please? Thanks.

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• C# Reflection - How can I tell if object o is of type KeyValuePair and then cast it?

  - by Logan

  Hi All I'm currently trying to write a Dump() method from LinqPad equivalent iin C# for my own amusment. I'm moving from Java to C# and this is an exercise rather than a business requirement. I've got almost everything working except for Dumping a Dictionary. The problem is that KeyValuePair is a Value type. For most other Value types I simply call the ToString method but this is insufficient as the KeyValuePair may contain Enumerables and other objects with undesirable ToString methods. So I need to work out if it's a KeyValuePair and then cast it. In Java I could use wildcard generics for this but I don't know the equivalent in C#. Your quest, given an object o, determine if it's a KeyValuePair and call Print on its key and value. Print(object o) { ... } Thanks!

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• Will C++1x support __stdcall or extern "C" capture-nothing lambdas?

  - by Daniel Trebbien

  Yesterday I was thinking about whether it would be possible to use the convenience of C++1x lambda functions to write callbacks for Windows API functions. For example, what if I wanted to use a lambda as an EnumChildProc with EnumChildWindows? Something like: EnumChildWindows(hTrayWnd, CALLBACK [](HWND hWnd, LPARAM lParam) { // ... return static_cast<BOOL>(TRUE); // continue enumerating }, reinterpret_cast<LPARAM>(&myData)); Another use would be to write extern "C" callbacks for C routines. E.g.: my_class *pRes = static_cast<my_class*>(bsearch(&key, myClassObjectsArr, myClassObjectsArr_size, sizeof(my_class), extern "C" [](const void *pV1, const void *pV2) { const my_class& o1 = *static_cast<const my_class*>(pV1); const my_class& o2 = *static_cast<const my_class*>(pV2); int res; // ... return res; })); Is this possible?

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• git, SSH_ASKPASS on windows

  - by Martin Schreiber

  I am writing a graphical git frontend for Linux and Windows (MSEgit) based on MSEide+MSEgui. MSEgit has an internal console window which communicates with git by pipes. On Linux it uses a PTY so SSH asks for key unlocking passwords on the PTY. On Windows I wrote a small password entry application and set the SSH_ASKPASS environment variable accordingly. SSH calls the password application if git is started with CreateProcess() dwCreationFlags DETACHED_PROCESS set but the password entry window will not be focused, its taskbar icon flashes instead. SSH does not run the password application if FreeConsole() is called to be sure that there is no attached console to MSEgit and git is started without DETACHED_PROCESS but CREATE_NO_WINDOW instead. I assume a Windows equivalent of POSIX setsid() should be called. How can I force SSH to use SSH_ASKPASS without the DETACHED_PROCESS flag? If this is not possible, how can I ensure that the password entry window is focused?

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• Obtain all keys of a Neo4j index

  - by MattiSG

  I have a Neo4j database whose content is generated dynamically from a big dataset. All “entry points” nodes are indexed on a named index (IndexManager.forNodes(…)). I can therefore look up a particular “entry point” node. However, I would now like to enumerate all those specific nodes, but I can't know on which key they were indexed. Is there any way to enumerate all keys of a Neo4j Index? If not, what would be the best way to store those keys, a data type that is eminently non-graph-oriented? UPDATE (thanks for asking details :) ): the list would be more than 2 million entries. The main use case would be to never update it after an initialization step, but other use cases might need it, so it has to be somewhat scalable. Also, I would really prefer avoiding killing my current resilience abilities, so storing all keys at once, as opposed to adding them incrementally, would be a last-resort solution.

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• C++ associative array with arbitrary types for values

  - by Gerald Kaszuba

  What is the best way to have an associative array with arbitrary value types for each key in C++? Currently my plan is to create a "value" class with member variables of the types I will be expecting. For example: class Value { int iValue; Value(int v) { iValue = v; } std::string sValue; Value(std::string v) { sValue = v; } SomeClass *cValue; Value(SomeClass *v) { cValue = c; } }; std::map<std::string, Value> table; A downside with this is you have to know the type when accessing the "Value". i.e.: table["something"] = Value(5); SomeClass *s = table["something"].cValue; // broken pointer Also the more types that are put in Value, the more bloated the array will be. Any better suggestions?

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• How select data from SQLite table where date = week of year?

  - by vovaxo

  I have table expense: "create table " + Expense.TABLE_NAME + "(" + Expense.ID + " integer primary key autoincrement not null, " + Expense.CATEGORY_ID + " integer, " + Expense.ITEM + " text, " + Expense.PRICE + " real, " + Expense.DATE + " date, " + Expense.TIME + " time);"; And I want to select Expense.PRICE where Expense.DATE = current day/week/month. I tried to do this cursor = mDB.rawQuery("select " + Expense.PRICE + " where " + " (strftime('%W', " + Expense.DATE + "))" + "=" + week, null); where week is week = calendar.get(Calendar.WEEK_OF_YEAR); but it gives an error in cursor: 09-15 09:32:02.647: E/AndroidRuntime(18939): Caused by: java.lang.NullPointerException 09-15 09:32:02.647: E/AndroidRuntime(18939): at com.pllug.summercamp.expensemanager.DataAdapter.getPrice(DataAdapter.java:242)

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• Trouble applying a simple template

  - by Adam S

  I'm having trouble applying a template to my checkboxes. I have the following template: <ControlTemplate x:Key="TriStateRed" TargetType="{x:Type CheckBox}"> <ControlTemplate.Triggers> <Trigger Property="IsChecked" Value="{x:Null}" > <Setter TargetName="path" Property="Data" Value="M 0 2.5 A 5 2.5 0 1 1 5 5 L 5 8 M 5 10 L 5 10" /> <Setter TargetName="path" Property="Stroke" Value="Red" /> </Trigger> </ControlTemplate.Triggers> </ControlTemplate> However, visual studio gives me the following error: Cannot find the Trigger target 'path'. (The target must appear before any Setters, Triggers, or Conditions that use it.) Can anyone make sense of this?

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• Accessing inter-schema tables and relations in hibernate

  - by nitesh

  There is a typical situation being faced where different tables are scattered through different schemas in Oracle database and they are related to each other (encompassing all different types of relations). How can they be represented in Hibernate using annotations as when a sessionfactory handle is created for one schema, tables in that schema can't access other related tables (foreign key relation to tables in other schema)? For a query like following, exception is thrown - "from table1 as model where model.table2Name.table2column = "+foo Exception comes as - org.hibernate.QueryException: could not resolve property: table2column of: com.test.table1 [from com.test.table1 as model where model.table2Name.table2column = 1] Here table1 and table2 are present in different schemas.

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• How to insert into a table with just one IDENTITY column (SQL Server CE)

  - by Hei

  Hello I am trying to insert a value in a one IDENTITY column Table in SQL Server CE 3.5. I Tried the following: INSERT Target DEFAULT VALUES INSERT Target (ID) VALUES (DEFAULT) INSERT Target (ID) VALUES () But none of them worked. This is the SQL command I used to create the table (Using SQL Server Management Studio): CREATE TABLE Target( ID int NOT NULL IDENTITY (1, 1) PRIMARY KEY ); Microsoft help site (http://msdn.microsoft.com/en-us/library/ms174633%28SQL.90%29.aspx) mentions that DEFAULT values are not valid for identity columns however they do not mention any alternative. They mention something about uniqueidentifier and ROWGUID but I have not been able to make it work. I would appreciate any pointers on how to solve this problem or links to documentation about valid sql commands for sql server CE. Thank you

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• BeanUtils getPropertyOfMapBean

  - by dx-cp

  Hi, Im wondering if it is possible to get data from property which is map cotaining pairs Key-StringArray (Map) in BeanUtils library. I just simply need to access one of array elements by calling propertyName=string[0]. Current version (1.8.3) does not support indexed properties. If you look into their code you will find in class PropertyUtilsBean in method getPropertyOfMapBean: if (resolver.isIndexed(propertyName) || resolver.isMapped(propertyName)) { throw new IllegalArgumentException( "Indexed or mapped properties are not supported on" + " objects of type Map: " + propertyName); } way too bad:-( Have any of you any tip how to do it somehow differently?

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• IntelliJ Split Window Navigation

  - by jmquigley

  If I split the editor window (horizontal or vertical) into N tab groups, how do I switch/toggle from one tab group to another via the keyboard? If all of the tabs are in the same group you can switch from each tab easily (CTRL + right/left arrow), but when they're in separate tab groups I can't. I've searched through the key mappings and have not found one that seems to accomplish this. I know I can use the mouse, but I'm trying to find ways to avoid the mouse and stay with the keyboard. TIA for any help on this.

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