Without the concatenation it runs fine, enormously faster than with the concatenation. Have checked and the result is fine as well. Thanks again.
RBS On Tue, Oct 16, 2012 at 11:38 PM, Igor Tandetnik <itandet...@mvps.org> wrote: > On 10/16/2012 6:29 PM, Bart Smissaert wrote: >> >> Actually, it really is slow, made worse by the fact that there is not >> one grouping >> field (value in my example), but three. I am running your SQL now, >> concatenating >> these 3 fields, but still running and looks will be a long time. >> Will have to improve it with indexes and maybe avoiding the concatenation. > > > This would avoid concatenation: > > > update MyTable set Group_Marker = ( > select count(*) from MyTable t1 > where t1.ID <= MyTable.ID and not ( > select (t2.Value1=t1.Value1 and t2.Value2=t1.Value2 and > t2.Value3=t1.Value3) > > from MyTable t2 where t2.ID < t1.ID > order by t2.ID desc limit 1 > ) > ); > > The only index that would be helful is one on ID, which I suspect you might > already have. > > -- > Igor Tandetnik > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
