> Le 20 juil. 2017 à 08:45, Clemens Ladisch <clem...@ladisch.de> a écrit : > > Rowan Worth wrote: >> On 18 July 2017 at 21:43, David Raymond <david.raym...@tomtom.com> wrote: >>> You can run "begin deferred transaction" then walk away for 3 months >>> without upsetting anything. If you need the precise timing then why not >>> just use "begin immediate"? >> >> IMMEDIATE would take a RESERVED lock which is clearly not desired in this >> case -- the reader only wants a SHARED lock so as to minimise contention >> with the writer. > > Then to take a SHARED lock, you have to actually read something from the > database, e.g.: > > BEGIN DEFERRED TRANSACTION; > PRAGMA user_version;
Yes, that's exactly that. See https://github.com/groue/GRDB.swift/blob/2526e0a2f7097acbb71e41fb55baeda9d98c441d/GRDB/Core/DatabasePool.swift#L516-L540 for an implementation For a description of the benefits that users can have from such precision snapshotting, read: https://github.com/groue/GRDB.swift/blob/master/README.md#advanced-databasepool And on such robust ground, you can build very high-level constructs like https://github.com/RxSwiftCommunity/RxGRDB Gwendal Roué _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
