hi,
as Helen sayyou must commit previous transaction not close connection
regards,Karol Bieniaszewski

-------- Oryginalna wiadomość --------
Od: "'Andrew Zenz' [email protected] [firebird-support]" 
<[email protected]> 
Data: 04.02.2016  05:55  (GMT+01:00) 
Do: [email protected] 
Temat: RE: [firebird-support] system table behaviour 


 



  


    
      
      
      







Thanks Helen.

 

‘Tis starting to make some sense
now.

 

Unfortunately our application establishes
a connection to the FB server and remains active until shut down.  I can’t
terminate it and create a new one.  A ‘feature’ of the RAD we are
using.

 

You have given me an idea though, thanks.

 



Andrew Zenz

 

 











From:
[email protected] [mailto:[email protected]] 

Sent: Thursday, 4 February 2016
3:31 PM

To: [email protected]

Subject: Re: [firebird-support]
system table behaviour



 

  









Hello 'Andrew,



Thursday, February 4, 2016, 2:19:07 PM, you wrote:


 
  
   
  
  
  

  

  

  Hi.

  

  I am writing a small application for our support staff which includes the
  ability to see who is connected to a database using the query:

  

  SELECT M.MON$ATTACHMENT_ID, M.MON$USER, M.MON$REMOTE_ADDRESS,
  M.MON$TIMESTAMP, M.MON$REMOTE_PROCESS FROM MON$ATTACHMENTS M

  

  When the application first runs, it gets the correct number of records.

  

  If a user connects to the database and, without closing the application, I
  re-run the query, it doesn’t update the result.  That is, the list
  of connected users does not show the new connection.  Similarly if
  someone disconnects, the list is not updated.  Closing the application
  and running it again updates the result.
  
 






You don't have to close the application to refresh
the MON$ results, 

simply commit the transaction and run the query in a new transaction.  


 
  
   
  
  
  

  Using Flamerobin, the results are as expected.

  

  I tried using a stored procedure to give me the list (hoping that moving the
  query closer to the database might yield more timely results) but that
  didn’t work either.  I have also tried opening and closing the
  view and file.  Other user tables seem to work as you would expect.

  

  Do the system tables cache results or do they behave differently to user
  tables? 
  
 






The MON4 tables are in-memory structures.
 Queries on them run in a 

SNAPSHOT transaction.  That is, the statement provides a snapshot of 

the status of those items at the time the transaction started and will

not be "refreshed" by re-running the same query inside the same 

transaction.



The persistent system tables (RDB$...) behave like any regular table.



Helen














    
     

    
    


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