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Knowledge Base Article:IMW88 


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Another worktation is READING or WRITING to this database

Article created: Oct 21 2002, updated: Oct 21 2002

Background:  Intersection Magic keeps track of users who are accessing the database. At any one time there may be many people READING from the database. However, if anyone is writing to the database, no one else may READ or WRITE at the same time.
If you are attempting to READ when you get this message, then another use has opened the database for WRITING. If you attempting to WRITE to the database, then another user is READING the database.
Note: This message can also be caused by the program having crashed during a READ or WRITE operation and not released its lock on the database.

Status:  Intended behaviour - description
Keywords:  reading,writing,crash,workstation,reset,user
Categories:   *Errors / crashes* *Networking*

Explanation:
IMW maintains a file in the database directory called CITYACC.SEM that tracks the current users of the database. Each time a user begins reading or writing, and entry is made. If another user attempts to access the database in a way that could adversly affect the operation of the program, the program reports this in the form of a warning. "Another workstation is READING / WRITING to this database".

If a user opens the database and the computer is turned off abruptly, or the program crashes, then the program will not have an opportunity to remove the entry from the .SEM file. This will result in any other attempted access to the database being rejected.

Solution:
If another user is indeed WRITING to the database, you must cancel this warning dialog and wait for that user to stop WRITING.

If no one is accessing the database, then the user list (semaphore file) must be reset. After making sure that everyone has disconnected from the database, select the "reset user list" option in the dialog. This will delete the .SEM file from the database directory. Access should be restored.

Another common problem is that of having a read-only attribute on the database or directory containing the database. This could also be caused by insuffient network access. All users must have read/write network access to all of the database files in order for the program to function properly.

Note the users menu contains an option to view current users. This will present a dialog listing all the names currently logged into the system. If users are logging in with unique names, this list can be used to identify exactly who has a lock on the database.
April 23, 2018 1:01PM

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