Think of transactions as cars and the rows as the paving stones of a paved car 
park, and writing data as parking your car. You cannot park two cars on the 
same paving stones at the same time without creating a collision. The second 
car will have to leave the car park and try again.

-----Ursprüngliche Nachricht-----
Von: sqlite-users [mailto:sqlite-users-boun...@mailinglists.sqlite.org] Im 
Auftrag von Marco Bambini
Gesendet: Montag, 26. März 2018 09:10
An: SQLite mailing list <sqlite-users@mailinglists.sqlite.org>
Betreff: [EXTERNAL] Re: [sqlite] what is server-process-edition?

Is there a better formal description about the "transactions may not overlap" 
sentence?
Is there any example about overlapping transactions?

--
Marco Bambini
http://www.sqlabs.com
http://twitter.com/sqlabs



>> The begin-concurrent branch
>> (https://sqlite.org/src/timeline?r=begin-concurrent&n=all) allows you
>> to say:
>>
>>    BEGIN CONCURRENT;
>>    -- various database reads and updates
>>    COMMIT;
>>
>> And to do that simultaneously in two or more database connections,
>> and have them all work.  Except, the concurrent transactions may not
>> overlap.  That is to say, content written by one may not be read or
>> written by another.  If the transactions do overlap, the second one
>> to try to COMMIT will get an SQLITE_BUSY_SNAPSHOT error and will be
>> forced to abandon its transaction and start over.
>>
>> The begin-concurrent branch is in production use in high-stress
>> environments.  We have not merged that branch to trunk (yet) because
>> it currently imposes extra overhead on all applications, even
>> applications that do not use BEGIN CONCURRENT.
>>
>> Another alternative is the newer server-process-edition branch
>> (https://sqlite.org/src/timeline?n=all&r=server-process-edition)
>> which you can read about here:
>> https://sqlite.org/src/artifact/0c6bc6f55191b690
>>
>> --
>> D. Richard Hipp
>> d...@sqlite.org
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 Gunter Hick | Software Engineer | Scientific Games International GmbH | 
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