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1. • • A junction, also called an NTFS (NTFS file system) junction point, is a feature of the NTFS file system. It is pointer to a directory on the local volume, similar to a symlink. It can be accessed through the Windows GUI (graphical user interface) in addition to the Windows command line.
     www.computerhope.com › jargon › j

     What is a Junction? - Computer Hope

2. Top results related to what is junction point?

   • What is the point of a junction table

     Top Answer

     Answered Jan 18, 2024 · 4 votes

     The use of the junction table takes your data to its lowest possible normalised level, it should be used where there is something that could be duplicated across multiple entires such as a date or a time.

     I cannot think of a specific example with a Chat and Chat User table, but one ive come across a lot is in relation to addresses.

     As individuals both you and myself could live at the same address, but at different times. It wouldnt be appropriate to hold a date of when I lived at an address in a user table (as I could live at multiple addresses). It also wouldnt be appropriate to record a date in the address table (as this could lead to multiple address lines), as such you should end up with tables with the following design and data.

     User_Table

     Address_Table

     Address_History_Table

     In this example U1 (John Smith) and U2 (Jane Smith) have both lived at address AD1(1 High Street) but not at the same time. In this example Jane moved in (02/01/2019) the day after John moved out (02/01/2019).

     U1 (John Smith), then moved into AD2 (2 High Street) from the 02/01/2019 with no end date. U3 (Rebecca Smith) lived in this address already (start_date of 01/08/1965) and lived there until 31/08/2022.

     From this we can identify that John and Jane havent lived together, while John and Rebecca did (From the 02/01/2019 to 31/08/2022).

     The use of the junction table will very much depend on your data. In your chat example if two users were in the same chat for the exact same time, could lead to a duplication if a time for example was recorded.

     A juntion table can sometimes just be three columns

     • Primary Key of the table
     • Foreign Key of the user table
     • Foreign Key of the chat table

     The junction table would then just be used to denote which chat linked to which user, and dosent need to contain any other information.

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     1/5

   • What is the point of having a key_t if what will be the key to access shared memory is the return value of shmget()?

     Top Answer

     Answered Jul 29, 2018 · 14 votes

     Yes, you need to use the shmid to access the shared memory (using shmat()) after you've opened it using shmget(). But the specific block of shared memory that you'll be accessing is based on the key that you are using i.e. different process wishing to communicate via the shm will need to use the same key. If you just used a random number as a key, you might get a clash with some other unrelated program.

     I was going to suggest taking a look at Beej's Guide to IPC but I see you've already found it :)

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     2/5

   • What is the necessity of junction tables?

     Top Answer

     Answered Mar 13, 2014 · 2 votes

     The way I see it, you have have several entities

     CREATE TABLE StudentType( Id Int PRIMARY KEY, Name NVarChar(50) );INSERT StudentType VALUES( (1, 'Basic'), (2, 'Advanced'), (3, 'SomeOtherCategory'));CREATE TABLE Student( Id Int PRIMARY KEY, Name NVarChar(200), OtherAttributeCommonToAllStudents Int, Type Int, CONSTRAINT FK_Student_StudentType FOREIGN KEY (Type) REFERENCES StudentType(Id))CREATE TABLE StudentAdvanced( Id Int PRIMARY KEY, AdvancedOnlyAttribute Int, CONSTRIANT FK_StudentAdvanced_Student FOREIGN KEY (Id) REFERENCES Student(Id))CREATE TABLE StudentSomeOtherCategory( Id Int PRIMARY KEY, SomeOtherCategoryOnlyAttribute Int, CONSTRIANT FK_StudentSomeOtherCategory_Student FOREIGN KEY (Id) REFERENCES Student(Id))

     • Any attributes that are common to all students have columns on the Student table.
     • Types of student that have extra attributes are added to the StudentType table.
     • Each extra student type gets a Student<TypeName> table to store its specific attributes. These tables have an optional one-to-one relationship with Student.

     I think that your "straw-man" junction table is a partial implementation of an EAV anti-pattern, the only time this is sensible, is when you can't know what attributes you need to model, i.e. your data will be entirely unstructured. When this is a real requirment, relational databases start to look less desirable. On those occasions consider a NOSQL/Document database alternative.

     A junction table would be useful in the following scenario.

     Say we add a Class entity to the model.

     CREATE TABLE Class( Id Int PRIMARY KEY, ...)

     Its concievable that we would like to store the many-to-many realtionship between students and classes.

     CREATE TABLE Registration( Id Int PRIMARY KEY, StudentId Int, ClassId Int, CONSTRAINT FK_Registration_Student FOREIGN KEY (StudentId) REFERENCES Student(Id), CONSTRAINT FK_Registration_Class FOREIGN KEY (ClassId) REFERENCES Class(Id))

     This entity would be the right place to store attributes that relate specifically to a student's registration to a class, perhaps a completion flag for instance. Other data would naturally relate to this junction, pehaps a class specific attendance record or a grade history.

     If you don't relate Class and Student in this way, how would you select both, all the students in a class, and all the classes a student reads. Performance wise, this is easily optimised by indices on key columns.

     When a many-to-many realtionships exists without any attributes I agree that logically, the junction table needn't exist. However, in a relational database, junction tables are still a useful physical implmentaion, perhaps like this,

     CREATE TABLE StudentClass( StudentId Int, ClassId Int, CONSTRAINT PK_StudentClass PRIMARY KEY (ClassId, StudentId), CONSTRAINT FK_Registration_Student FOREIGN KEY (StudentId) REFERENCES Student(Id), CONSTRAINT FK_Registration_Class FOREIGN KEY (ClassId) REFERENCES Class(Id))

     this allows simple queries like

     // students in a class?SELECT StudentIdFROM StudentClassWHERE ClassId = @classId-// classes read by a student?SELECT ClassIdFROM StudentClassWHERE StudentId = @studentId

     additionaly, this enables a simple way to manage the relationship, partially or completely from either aspect, that will be familar to relational database developers and sargeable by query optimisers.

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     3/5

   • What is the point of views in pandas if it is undefined whether an indexing operation returns a view or a copy?

     Top Answer

     Answered Jan 20, 2016 · 11 votes

     Great question!

     The short answer is: this is a flaw in pandas that's being remedied.

     You can find a longer discussion of the nature of the problem here, but the main take-away is that we're now moving to a "copy-on-write" behavior in which any time you slice, you get a new copy, and you never have to think about views. The fix will soon come through this refactoring project. I actually tried to fix it directly (see here), but it just wasn't feasible in the current architecture.

     In truth, we'll keep views in the background -- they make pandas SUPER memory efficient and fast when they can be provided -- but we'll end up hiding them from users so, from the user perspective, if you slice, index, or cut a DataFrame, what you get back will effectively be a new copy.

     (This is accomplished by creating views when the user is only reading data, but whenever an assignment operation is used, the view will be converted to a copy before the assignment takes place.)

     Best guess is the fix will be in within a year -- in the mean time, I'm afraid some .copy() may be necessary, sorry!

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     4/5

   • What is point of type casting?

     Top Answer

     Answered Dec 29, 2015 · 7 votes

     char is an integral type in Java, and when you perform arithmetic the result is an int (JLS-4.2.2. Integer Operations says, in part, the numerical operators, which result in a value of type int

     or long

     and adds that does include the additive operators +

     and -

     ).

     char c = 'A';System.out.printf("'%c' = %d%n", c, (int) c);int d = (c - 'A' + 'a'); // c - 65 + 97System.out.printf("'%c' = %d%n", (char) d, d);

     And I get

     'A' = 65'a' = 97-

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     5/5

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3. People also ask

   What is a junction point?

   • Kelly C. Bourne, in Application Administrators Handbook, 2014 A junction point is essentiallya directory that actually points to another directory. The idea here is to create and use a junction point so the application uses a different drive but doesn’t know it.

   Junction Point - an overview | ScienceDirect Topics

   www.sciencedirect.com/topics/computer-science/junction-point

   See all results for this question

   What is a junction point in Linux?

   • Junction points are reparse points and operate similarly to symbolic links in Unix or Linux, but are only defined for directories, and may only be absolute paths on local filesystems. They are created and behave in a similar way to hard links, except that if the target directory is renamed, moved, or deleted, the link will no longer be valid.

   NTFS links - Wikipedia

   en.wikipedia.org/wiki/NTFS_links

   See all results for this question

   What are NTFS junction points?

   • Junction Points (also commonly referred to as NTFS Junction or Directory Junction) are a type of reparse point which contains link to a directory that acts as an alias of that directory. Junction point work similar to a symbolic link but only for directories.

   NTFS Junction Points - GeeksforGeeks

   www.geeksforgeeks.org/ntfs-junction-points/

   See all results for this question

   Are junction points symbolic links?

   • Junction Points and Symbolic Links are both Reparse Points, but Junction Points most definitely are not Symbolic Links! Oh and the table is wrong on one count also. The target of a Junction Point must exist upon creation, but it may indeed be removed later on.

   What is the difference between NTFS Junction Points and Symbolic Links?

   stackoverflow.com/questions/9042542/what-is-the-difference-between-ntfs-junction-points-and-symbolic-links

   See all results for this question

4. www.computerhope.com › jargon › jWhat is a Junction? - Computer Hope

   www.computerhope.com › jargon › j

   • Cached

   Nov 13, 2018 · A junction, also called an NTFS (NTFS file system) junction point, is a feature of the NTFS file system. It is pointer to a directory on the local volume, similar to a symlink. It can be accessed through the Windows GUI (graphical user interface) in addition to the Windows command line.

5. www.geeksforgeeks.org › ntfs-junction-pointsNTFS Junction Points - GeeksforGeeks

   www.geeksforgeeks.org › ntfs-junction-points

   • Cached

   Sep 10, 2020 · Junction Points (also commonly referred to as NTFS Junction or Directory Junction) is a type of reparse point which contains a link to a directory that acts as an alias of that directory. Junction points are a Windows exclusive feature, absent in other operating systems.

6. stackoverflow.com › questions › 9042542What is the difference between NTFS Junction Points and ...

   stackoverflow.com › questions › 9042542

   • Cached

   Jan 28, 2012 · A symbolic link, as created by Windows, is much similar to a directory junction, but unlike a directory junction it can point to a file or a remote network file or directory. The target may be defined as a path relative to the symbolic link position, or an absolute path in the current volume or another one.

   • Symbolic links have more functionality, while junctions almost seem to be a legacy feature because of their limitations, but the security implicati...
   • The places I find the most useful for the differences: http://blogs.msdn.com/b/junfeng/archive/2006/04/15/576568.aspx. http://www.hanselman.com/b...
   • Functionally, in windows, once created, there is no real difference. However, there are significant differences between them in what they can do.
   • Link Shell Extension, http://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html, is a great tool for creating and viewing many kinds of lin...
   • In addition to the excellent answer from u8it: If anyone is interested in the difference in behavior in Windows File Explorer in Windows 10: drag...
   • Symbolic links have been introduced very recently in Windows : as from Vista. Symbolic links should not be regarded as an alternative to the exist...

7. www.geeksforgeeks.org › creating-junction-pointsCreating Junction Points - GeeksforGeeks

   www.geeksforgeeks.org › creating-junction-points

   • Cached

   Oct 5, 2020 · Junction Points (also commonly referred to as NTFS Junction or Directory Junction) is a type of reparse point which contains a link to a directory that acts as an alias of that directory. Junction points are a Windows exclusive feature, absent in other operating systems.

8. superuser.com › questions › 67870What is the difference between NTFS hard links and directory ...

   superuser.com › questions › 67870

   • Cached

   Hard Link: A link to a file on the same volume (drive letter) only. Every file (file's data) has at least 1 hard link (file's name). Deleting all hard links effectively deletes the file. Junction: A link to a directory on the same or different volume (drive letter) but not to a remote directory.

   Code sample

   /D Creates a directory symbolic link. Default is

     a file symbolic link.

   /H Creates a hard link instead of a symbolic link.

   /J Creates a Directory Junction.

   Link specifies the new symbolic link name....

   See more on superuser

9. en.wikipedia.org › wiki › NTFS_linksNTFS links - Wikipedia

   en.wikipedia.org › wiki › NTFS_links

   • Cached

   Symbolic links to directories or volumes, called junction points and mount points, were introduced with NTFS 3.0 that shipped with Windows 2000. From NTFS 3.1 onwards, symbolic links can be created for any kind of file system object.

10. www.sciencedirect.com › junction-pointJunction Point - an overview | ScienceDirect Topics

    www.sciencedirect.com › junction-point

    A junction point is essentially a directory that actually points to another directory. The idea here is to create and use a junction point so the application uses a different drive but doesn’t know it.