Thanks guys! You rock! Transactions did the trick. @Mark I'll check out that presentation you mentioned.
I guess I discounted the flash write as being the bottleneck, because even at a slow 1.5Mbps write speed I expected better performance (<5-10ms) for writing a few hundred bytes. On Sep 11, 4:14 am, Mark Murphy <[email protected]> wrote: > On Fri, Sep 10, 2010 at 10:11 PM, Sheado <[email protected]> wrote: > > The issue: > > SQLiteDatabase.update(...) takes anywhere from 30ms to 700ms on a > > simple update (on a Motorola Droid). I'm not sure why there's such a > > huge range in the timing, but despite that it still means that in the > > best case updating one column in 30 rows will take at least one second > > - in the best case! On average updating 30-40 rows is taking me 3-4 > > seconds - this is crazy slow - like 1985 computer slow! > > No, it's like flash slow. Please watch Brad Fitzpatrick's "Writing > Zippy Android Apps" presentation from the 2010 Google I|O conference. > He covers this very point. > > > I've tried: > > * update(...) with ContentValues > > * update with execSql() > > * add/removing indices on the columns in question > > None of those should have any effect. You're assuming the problem is > with the CPU. It's not. It is with the flash writes. You need to cut > down on the number of flash writes. > > > Is there anything else I can try to improve performance? For example, > > is there any way to update multiple rows with one statement? > > As the others on this thread pointed out, use transactions. That will > turn ~30 individual transactions (each with its own set of flash > write) into one. > > -- > Mark Murphy (a Commons > Guy)http://commonsware.com|http://github.com/commonsguyhttp://commonsware.com/blog|http://twitter.com/commonsguy > > _The Busy Coder's Guide to *Advanced* Android Development_ Version 1.9 > Available! -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
