What is Select count(*) from ... doing?

I don't understand the behaviour of select count(*). I create a table with 1.5 million rows and commit the insert. Sometime later, whether minutes or hours, I do a select count(*) from the table. With Oracle's Server Manager window open, I can see that the tablespace with the newly created table (and no other concurrent activity) is being accessed with twice as many writes as reads. Furthermore, the select count(*) takes a very long time.

Does anybody know what Oracle is doing? Also, why doesn't Oracle maintain a row count?

Marty Himmelstein
marty.himmelstein_at_valley.net Received on Thu Jul 27 1995 - 00:00:00 CEST