jwcolby
jwcolby at colbyconsulting.com
Tue Jun 3 19:20:08 CDT 2008
Francisco, Thanks for that. It was just idle curiosity. I really need to stay busy so that I don't get struck with that idle curiosity stuff. I didn't time the initial query running nor the rollback, but it didn't seem to be markedly different one way or the other. John W. Colby www.ColbyConsulting.com Francisco Tapia wrote: > The process that is occurring is that the system is "rolling back" the > transaction as it existed in the transaction log. How quick depends on what > disk the transaction log is on in order re-process it all. I have noticed > in my experience that rolling back an action does not take as long as doing > something, but it does depend on the number of records processed etc. as > always ymmv > > -- > Francisco > > On Tue, Jun 3, 2008 at 1:47 PM, jwcolby <jwcolby at colbyconsulting.com> wrote: > >> Just idle curiosity, does an "undo query" happen at the same >> rate as a "do query"? >> >> I started a query running to append records from a ninety >> million record table to a table that contains a subset of >> the fields. Basically I have a denormalized source table >> with name, name2, name3 etc fields. Each of these have >> fname, mname, gender, age etc. Since these are denormalized >> "family" records, there are fewer Name2 records than Name1, >> fewer still Name3 etc. >> >> I neglected to put in a "where name2 is not null" clause and >> 30 minutes into the second append I realized that. I >> canceled the query and it is still "undoing" the query. >> Which led me to wonder the relative efficiency of "doing" vs >> "undoing". >> >> No Indexes in place on the target table of course. >> >> Any ideas on the relative efficiencies? Is undoing an >> append much slower than the append? >> >> -- >> John W. Colby >> www.ColbyConsulting.com >> _______________________________________________ >> dba-SQLServer mailing list >> dba-SQLServer at databaseadvisors.com >> http://databaseadvisors.com/mailman/listinfo/dba-sqlserver >> http://www.databaseadvisors.com >> >> > >