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List:       sqlite-users
Subject:    [sqlite] Feature request
From:       Simon Slavin <slavins () hearsay ! demon ! co ! uk>
Date:       2009-05-21 4:59:27
Message-ID: B812C28E-240A-4E3C-83BE-6CFF80DDCBC7 () hearsay ! demon ! co ! uk
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I welcome discussion of a feature request I intend to make.  Please  
suggest better function names, more considerations, or anything else  
interesting.



int sqlite3_change_count(sqlite3*)

Returns an integer which is incremented whenn a change is made to any  
table in the database.  May be the value stored in bytes 24..27 of  
file header or something else if that's not what I really want.

Considerations:

I don't mind whether 'a change' means the number of 'COMMIT's, the  
number of change commands that have been committed, the number of rows  
changed, or the number of fields changed.

I'm not too worried if it changes when no detectable change has been  
made (e.g. writing a value to a field that's already set to that  
value), but it should not stay the same when something really does  
change.

The value should decrease iff wrap-around value has been reached.   
However, normal programming practice would check to see whether the  
value has changed, rather than whether the value has increased.

If it's undesirable to introduce yet another function to the library,  
alternatives would be to introduce a read-only PRAGMA value, or  
something like 'now', whatever that is.



This is related to a thread started by Ben Harper on May the 4th.  I  
happen to want the same thing he did for two reasons: so I can tell if  
another app is messing with my data behind my back, and so I can  
compare two copies of a database for synchronisation or crash- 
recovery.  I'm aware I can read the header manually, or check the  
file's modification timestamp, but I would like the function for  
neatness' sake.

Simon.
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