I'm not sure what you mean...? _Nik
On Mar 18, 2009, at 2:23 AM, pi song wrote: > Would not that be more efficient to do it in batch? Like an entry in > transaction means a block of deletions? If there is a crash during > dropping operation then the journal can be looked up and replayed. > > Pi Song > > On Wed, Mar 18, 2009 at 12:05 PM, Jim Wilcoxson <[email protected]> > wrote: >> Drop is executed within a transaction, which means that every record >> you touch has to be backed up to the journal first, then modified in >> the database. I'm guessing that if you use pragma synchronous=off, >> it >> would speed up the drop index, but you'd take a chance on corrupting >> the database if the machine crashed during the drop. >> >> It would probably be faster to make a copy of the database (all >> sequential I/O), then drop the index with synchronous=off in one of >> the copies (no journal I/O), then use vacuum if you want to really >> clean up the DB. If something goes wrong, you still have your backup >> copy. >> >> I haven't actually tried this; let us know if it makes a big >> difference. >> >> Jim >> >> On 3/17/09, Nikolas Stevenson-Molnar <[email protected]> wrote: >>> Hi, >>> >>> I'm trying to drop an index on a table with about 8 million rows and >>> it's taking a very long time. I can understand why building the >>> index >>> would take some time, but why dropping it? And is there any way to >>> speed it up? >>> >>> Thanks! >>> _Nik >>> _______________________________________________ >>> sqlite-users mailing list >>> [email protected] >>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >>> >> >> >> -- >> Software first. Software lasts! >> _______________________________________________ >> sqlite-users mailing list >> [email protected] >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >> > _______________________________________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
