No worries, I had figured you meant this applied to multiple read statements.
RBS On Thu, Jan 18, 2018 at 9:24 AM, R Smith <[email protected]> wrote: > > On 2018/01/17 4:26 PM, Bart Smissaert wrote: > >> 3. Start a transaction and hold the DB read locks for the duration of >>> >> your application (again, if it won't need writing) >> >> I had a look at this but couldn't see a speed increase. >> This was for a single statement, so that is repeated (in a >> loop) sqlite3_step, sqlite3_column_xxx etc. >> In what situation should this increase read speed? >> > > Apologies, should have been more clear - this will increase the speed > between queries FOR consecutive queries, not so much inside any single > query. > > To see why is easy, the loop amounts to either: > > // Slower loop: > for each q in queries do { > Acquire read lock; > Prepare; > Loop query results; > Release readlock; > } > > - OR - > > // Faster loop: > Start Transaction; > Acquire read lock; > for each q in queries do { > Prepare; > Loop query results; > } > Release readlock; > End Transaction; > > (This is very simplified and not technically 100% accurate how SQLite does > it, but you get the idea). > > > > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list [email protected] http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
