Weird behavior of the table with unique index

Hello, all;

I am having a weird problem with a simple SELECT statement, that I've never seen before.

I have a table, that has two columns as a primary key (which is an unique index). Table is kind of big (around 300,000 rows).

Let's say that primary key is (COLUMN1, COLUMN2).

I am running "Explain plan" on a following statement SELECT * FROM TABLE
WHERE COLUMN2 = lv_column2

     AND COLUMN1 = lv_column1

Explain plan shows me "Full table scan" instead of "Unique index scan".

Even if I put a hint on this unique index, I am getting "Full index scan"

Any ideas?????????????????????

Thanks for your help

Alla

P.S. Version of Oracle used is 7.3.3. Received on Sun Feb 07 1999 - 00:00:00 CET