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What are .LBD Files For?

Every time I open a Microsoft Access Database, it creates a .LDB file as well.  What is the purpose of this file?
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ssteeves
Asked:
ssteeves
1 Solution
 
Bundles031799Commented:
As far as i knew it was the lock database file. It controls the locking for the database.
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RRRCommented:
Then you are closing this mdb file the ldb file is gone (if you didn't close this mdb by task manager).
So, it save the users names that are currently opened the mdb and working now or they are opened and closed but this file steel locked by one or more users (example: xxx have opened this mdb file and he is working now. OK, but yyy opened this mdb file too and in ldb file you have user name of xxx and now user name of yyy.
If yyy closed the file after his changes and xxx steel working so ldb steel have xxx and yyy names. After all of users will close this mdb file the ldb file will be deleted ).

Good Luck
RRR.
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Jim Dettman (Microsoft MVP/ EE MVE)PresidentCommented:
ssteeves,

 The .LDB file is used to record the machine and user name.  It's comprised of 255 slots x 64 bytes. It's total size will never exceed 16K (approx).  When Access writes an entry into a slot, it also puts a corresponding entry in the DBH (Database Header page).  The DBH is the first page of the database and stores the status of the user in a two byte field (A95 and up).

  Access also uses it to place extended byte locks with the OS or NOS that controls the directory where the MDB resides.  That is, it uses the .LDB file name to place locks on parts of the file that don't exist.  By doing this, Access can use any locking scheme it wants without ever physically writing locks to disk.

  It is created when the first user logs in to the database and starting with A95, is deleted when the last user exits the database (this was done for performance reasons and aided with replicated databases).  This means that it is critical for all users to have full read/write/delete priviledges for the directory where the MDB resides.

  You can download JETLOCK.EXE from MSFT, which contains the utility LDBVIEW.EXE, which allows you to view the contents of the file.  It also contains a white paper that discusses JET locking in detail.

  For A95 and up MSFT has also made available a .DLL called MSLDBUSR.DLL, which you can use to read the contents of the .LDB programatically (there is code for A2 that can be used in place of the DLL).

Jim.
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brewdogCommented:
JDettman: I've never seen that explanation before. Where did you find that? Good information!
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blakeh1Commented:
One thing to keep in mind, if multiple users are going to be using the database is that they must have read, write/modify, create and delete right to the directory where the database is stored so they can modify the ldb, otherwise it will open read-only or give message it is being modified
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ssteevesAuthor Commented:
What's the URL to the MSFT site?
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ssteevesAuthor Commented:
Never mind.  I found it.
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