Why the difference?

I have a file with about 800,000 records from which I need to extract one month's worth of data (about 30,000) records.

insert column_names into extractmonth
(select column_names from fullfile where year = 1999 and month = 4);

runs at about 2.5 hours.

create table extractmonth as
select column_names from fullfile where year = 1999 and month = 4;

runs at about 2.5 seconds.

There is an index on year and month on full file.

Any ideas on what causes the difference? Received on Tue Apr 02 2002 - 15:14:12 CST