On 05/29/2015 12:59 PM, Zaumseil Ren? wrote: > On 05/27/2015 11:59 PM, Wade, William wrote: > >>> 3) The writing thread prefers to delete any existing file. If it can't do >>> that (some readers currently have the file open) it gains an exclusive >>> read/write lock (consistent with no reader has a transaction in progress) >>> and truncates the file to zero length, writes its new header (including his >>> own uuid, indicating that this is logically a new file). When existing >>> readers get around to reading again, they will check that uuid, and handle >>> the change in writers "gracefully." >>> >> But instead of using a regular SQL transaction to drop all the old >> tables, use the backup API to clobber the existing database with the new >> one. >> >> https://www.sqlite.org/c3ref/backup_finish.html >> >> Using the backup API, the clobber operation is still done as a regular >> SQLite transaction - so all the locking and notifying of other clients >> gets done right. The amount of IO (and CPU) required should depend on >> the size of the new db only, not the existing db size. And it won't >> matter if the existing db is corrupt or not - as the backup API never >> actually examines the contents of the existing database. >> >> Dan > Interesting idea. Could this also a solution to my problem described in the > thread "emptying tables"?
Maybe. Using the backup API to clobber one database with another featuring a bunch of empty tables is likely quicker than actually deleting all the data from the original. Dan. > > > Rene > > Kernkraftwerk Goesgen-Daeniken AG > CH-4658 Daeniken, Switzerland > > Diese Nachricht (inkl. Anhaenge) beinhaltet moeglicherweise vertrauliche oder > gesetzlich geschuetzte Daten oder Informationen. Zum Empfang derselben ist > (sind) ausschliesslich die genannte(n) Person(en) bestimmt. Falls Sie diese > Nachricht irrtuemlicherweise erreicht hat, sind Sie hoeflich gebeten, diese > unter Ausschluss jeder Reproduktion zu vernichten und den Absender umgehend > zu benachrichtigen. Besten Dank. > _______________________________________________ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
