Reverse a list

Peter Haworth pete at lcsql.com
Wed Feb 11 17:38:13 CET 2015


Hi Mike,
I doubt the sqlite approach will be faster than the other algorithms, but
36 seconds is still way too long to insert 10,000 lines. Could you post
your code?

Pete
lcSQL Software
On Feb 11, 2015 4:52 AM, "Mike Kerner" <MikeKerner at roadrunner.com> wrote:

> With sqlite on my box, doing the inserts via a transction took the time
> down to 36 seconds from 64, still not good enough.
>
> On Tue, Feb 10, 2015 at 11:58 AM, Mike Bonner <bonnmike at gmail.com> wrote:
>
> > You can find an example that uses begin transaction, and commit with a
> > repeat loop here:
> > http://forums.livecode.com/viewtopic.php?f=7&t=14145&hilit=+transaction
> >
> > On Tue, Feb 10, 2015 at 9:20 AM, Mike Kerner <MikeKerner at roadrunner.com>
> > wrote:
> >
> > > Mike B, no, I wasn't, proving once again that I don't know everything.
> > > Could you come over here, I need to do a mind meld.  I'll mess with
> that
> > in
> > > a minute.  I was also going to see if mySQL was any different, but I
> > > haven't done it, yet.
> > >
> > >
> > > On Tue, Feb 10, 2015 at 10:28 AM, Ali Lloyd <ali at runrev.com> wrote:
> > >
> > > > > Which v7 build is that?  Is it one we have or one coming up?
> > > >
> > > > I've just submitted the pull request so once it's reviewed it will be
> > > > merged and appear in the next build, so hopefully 7.0.2 RC 3.
> > > >
> > > > > Does LC 7 now do character references in constant (albeit a bit
> > slower)
> > > > time? Or linear? Or...
> > > >
> > > > In theory it should, yes. When you get char x of a native string, as
> > long
> > > > as the engine remembers that it is native, (which was fixed for a few
> > > > missing cases in bug 14504), it will act as if you used the codeunit
> > > chunk
> > > > instead, with the corresponding benefit of constant-time access.
> Indeed
> > > > this should also work for strings that the engine is storing as
> utf-16
> > > > which contain no combining characters or surrogate pairs.
> > > >
> > > > On 10 February 2015 at 15:11, Mike Bonner <bonnmike at gmail.com>
> wrote:
> > > >
> > > > > Thanks Ali!
> > > > >
> > > > > On Tue, Feb 10, 2015 at 8:10 AM, Mike Bonner <bonnmike at gmail.com>
> > > wrote:
> > > > >
> > > > > > Mike K, are you wrapping the inserts in a begin/commit block?  It
> > > > makes a
> > > > > > HUGE difference in speed. (otherwise, each is a separate
> > transaction
> > > > with
> > > > > > all the overhead.  If wrapped, its a single transaction, and so
> > much
> > > > > > faster.
> > > > > >
> > > > > > On Tue, Feb 10, 2015 at 7:36 AM, Geoff Canyon <gcanyon at gmail.com
> >
> > > > wrote:
> > > > > >
> > > > > >> Yay, that's great news. Does LC 7 now do character references in
> > > > > constant
> > > > > >> (albeit a bit slower) time? Or linear? Or...
> > > > > >>
> > > > > >> On Tue, Feb 10, 2015 at 4:50 AM, Ali Lloyd <ali at runrev.com>
> > wrote:
> > > > > >>
> > > > > >> > Apologies - hit send too early.
> > > > > >> >
> > > > > >> >
> > > > > >> > 6.7.1
> > > > > >> >
> > > > > >> > There are 2931 lines in tstart
> > > > > >> >
> > > > > >> > There are now 14655 lines in tstart
> > > > > >> >
> > > > > >> > revers(ta) took 427 ms
> > > > > >> >
> > > > > >> > qrevers(ta) took 6 ms
> > > > > >> >
> > > > > >> > Output OK
> > > > > >> >
> > > > > >> > krevers(ta) took 412 ms
> > > > > >> >
> > > > > >> > Output OK
> > > > > >> >
> > > > > >> >
> > > > > >> > 7.0.2 + bugfix
> > > > > >> >
> > > > > >> > There are 2931 lines in tstart
> > > > > >> >
> > > > > >> > There are now 14655 lines in tstart
> > > > > >> >
> > > > > >> > revers(ta) took 142 ms
> > > > > >> >
> > > > > >> > qrevers(ta) took 32 ms
> > > > > >> >
> > > > > >> > Output OK
> > > > > >> >
> > > > > >> > krevers(ta) took 258 ms
> > > > > >> >
> > > > > >> > Output OK
> > > > > >> >
> > > > > >> > On 10 February 2015 at 04:10, Kay C Lan <
> > lan.kc.macmail at gmail.com
> > > >
> > > > > >> wrote:
> > > > > >> >
> > > > > >> > > On Tue, Feb 10, 2015 at 11:58 AM, Geoff Canyon <
> > > gcanyon at gmail.com
> > > > >
> > > > > >> > wrote:
> > > > > >> > >
> > > > > >> > > > It seems that what we've lost with unicode/7 is the speed
> of
> > > > > >> character
> > > > > >> > > > references.
> > > > > >> > > >
> > > > > >> > >
> > > > > >> > > See Ali Lloyd's earlier response that the LC team have been
> > > > watching
> > > > > >> this
> > > > > >> > > tread and it's clear that 'inefficient code' has been
> > revealed.
> > > > The
> > > > > LC
> > > > > >> > team
> > > > > >> > > are working on it and believe that for none Unicode chunking
> > LC
> > > 7
> > > > > >> should
> > > > > >> > be
> > > > > >> > > as fast as LC 6. There will be some slow down when Unicode
> is
> > > > > >> involved.
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