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From "Suresh Thalamati (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-101) Limit on Number of log that can be created should be increased (current limit is 4194303)
Date Fri, 10 Dec 2004 00:22:09 GMT
Limit on Number of log that can be created should be increased (current limit is  4194303)
------------------------------------------------------------------------------------------

         Key: DERBY-101
         URL: http://nagoya.apache.org/jira/browse/DERBY-101
     Project: Derby
        Type: Improvement
  Components: Store  
    Reporter: Suresh Thalamati
 Assigned to: Suresh Thalamati 


Number of log files that can be generated on derby is limited to 2^22 -1 (4194303). Once this
linit is reached the insert/delete/update and reovery
may not work. I belive this limit could be hit in a very active system that does lot of inserts
and deletes. 

Just a approximate calculation how this limit could  be hit:
If we assume every 1 minute a 1MB (default log file size)log data is generated on a Derby
database. It will take just 291 days to hit the limit. 

419403 / (60 * 24) = ~291 days. 

291 days limit seems to be something a system that does lot of inserts/deletes can possibly
hit.  

It might be good idea to bump this limit to 2^32 -1 (4294967295).
By following the above assumption of 1M log data per minute with this 
linit it will take 8171.55 years: 
4294967295 / (60 * 24)  = 2982616.17 days  (8171.55 years) 
I guess this is a resonable limit!! 
---

One workaround for this problem is to change the log file size to 10 MB or more, that will
reduce the chance of hittig this limit. 

Please refer to derby-96 before fixing this issue, LSN format might get changed as part of
derby-96 fixes. 



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