> Ryan Johnson <ryan.johnson@...> writes: > Q1: Is C1 *always* NULL in a newly-inserted row, or does the application > sometimes insert some arbitrary value? > Q2: Does the transition from NULL to calculation(C2) mean something > special to the application? ... > Scenario 3: C1=NULL has a specific meaning in your application
C1=NULL is just a flag, whose only meaning is that update was not done yet on the recently inserted row. If in Windows Explorer you enter a folder with few thousand music files, then Explorer will show the list of files in the left column of detailed view instantaneously, but then it will begin slowly fill up other columns (Title, Artist, Album). My application is not an Explorer, but it has a similar pattern - show the list of item names ASAP and then prepare and store item attributes on the background. This is a pretty common pattern, I guess. So, in my minimal example C2 is the item url and C1 is item attributes (in reality there will be several columns with attributes: C11, C12, etc., but C1=NULL means that attributes were not prepared yet and C1!=NULL means that attributes are ready). > Scenario 2: C1=calculation(C2) is the default to use when the user fails to supply C1; No, in my case user does not touch the DB - he can only add or delete items, but all DB modifications are done by my app and I have a full control over all the values. All I need is to find the most efficient way to do that. Therefore, I do not believe that I need any triggers. I guess they will simply slow down insertion and update (however I did not measure this yet). In those rare cases when there is a need to reset attributes on an already existing item, I would rather delete the entire row and insert a new one and treat it as a completely new item. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
