Table Statistics Without Analyzing

Hi All --

consider the following scenario (row counts are approximate)

table_a has 24,500,000 rows
recent analyze (compute) of table has num_rows=24,500,000 in user_tables

rename table_a to table_a_old

create table_a as select * from table_a_old

select count(*) from table_a returns 24,500,000 select count(*) from table_a_old returns 24,500,000

select num_rows from user_tables

   where table_name = 'table_a_old' returns 24,500,000

select num_rows from user_tables

   where table_name = 'table_a' returns 24,685,000

close, but not exact

I have not analyzed the "new" table_a, so I'm assuming that the algorithm for "create table as select" does an analyze, similar to import. Is this correct? If so, it must be doing an estimate? If so, what %? If it doesn't do an analyze, how did user_tables get updated with num_rows?

Thanks!
Roy Received on Wed Sep 18 2002 - 22:11:24 CDT