On 2015-09-21 01:53 AM, Nicolas J?ger wrote: > hi, > > > Scott Robison wrote: > >> 3. Some time passes and some external process may alter the schema. >> > is it really possible ? if the answer is yes (I thought when a process open a > communication with > the DB, other processes can't alter the DB), for me that would mean that the > design(s) of the > program(s) wich communicates with the DB is bad.
This is the entire point of a database - allowing multiple things to see the data. A system which only allows one thread to read data is just a file-handler. > If I would like several process to communicate with a DB, I write first a > `demon` wich receive/send > the querries one by one to the DB and send one-by-one the results to the > processes. So with that > design I consider avoiding any overlapping. This is the magic - SQLite does all this for you so you don't need your programs to have daemons for multiple access. All they have to do is abide by the rules, and check the return values to see if the database is busy or not. There is one caveat here, when you would like to access a database file that is on a network from multiple sources, you need something else to control access, but that is just because network file-systems do not do locking well, and why even on the SQLite site it is suggested to use a client-server based system rather in that case.
