Autotrace

I run autotrace on a select statement. I want to know what mean
Cost, Card, Bytes in the output of the Autotrace.


0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=14 Bytes=98)
1 0 NESTED LOOPS (Cost=1 Card=14 Bytes=98)
2 1 TABLE ACCESS (FULL) OF 'EMP' (Cost=1 Card=14 Bytes=70)
3 1 INDEX (UNIQUE SCAN) OF 'PK_DEPT' (UNIQUE)


Thank's
Bensmail

Cost is the value selected by the optimizer. Optimizer selects the access path with the lowest cost value.

Card is cardinality.

Bytes specisfies the number of bytes accessed by the operation.