Re: [Virtuoso-users] Scope of log_enable and effect on deletes

[Quentin <qu...@gu...>]

 

>From the manual: 

>While log on and off setting alone is reset at the end of the transaction so that one does not end up with logging disabled by accident, the row-by-row autocommit mode causes the setting to be permanent inside the calling connection or web request. That is, for a SQL client the setting stays in effect until changed or disconnected and for a web request it stays in effect until the request is completed. 

http://docs.openlinksw.com/virtuoso/fn_log_enable/ 

If you want to determine whether the log is still disabled at a point in
time then this is one round-about way of doing it: 

>Attempt to disable transaction log that is disabled already result in an error. If the second parameter is passed and it is not equal to zero then the error is suppressed (and it's still possible to turn on or off autocommit). 

Set an exception handler to catch that error and set a flag to indicate
that the log was previously disabled. If there's no error/flag set then
proceed to re-enable the log. 

There might be better ways of doing it but that should work. 

-- 
Regards,
Quentin Serrurier.
GuidingHand.Solutions

On 2017-02-22 02:01, Davis, Daniel (NIH/NLM) [C] wrote: 

> I am not sure I understand the scope of the log_enable() procedure. If I call log_enable(2,1); in a stored procedure, I am sure that it will affect the entire connection, but, will it affect other connections as well. Would it, for instance, persist until reboot and affect other connections? How can I verify this - is there any command that will output the current transaction isolation level? 
> 
> Also, I have an inexplicable situation where my stored procedure loads a dataset in NTriples format into a graph, and then does some processing on that dataset. It is important for the processing that the graph be empty at the beginning, e.g. before the load. Try as I might, I seem to end-up in situations where the graph is not-empty, and I believe that this may be some interaction between log_enable() and the delete statement. I would think naively that log_enable(2,1); would have no effect on the serialization of row-level operations *IN THE SAME CONNECTION*, but perhaps I misunderstand. 
> 
> Dan Davis, Systems/Applications Architect (Contractor), 
> 
> Office of Computer and Communications Systems, 
> 
> National Library of Medicine, NIH 
> 
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