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Continuation of Notes


Notes:

DAVE> select count(*) from employee;

Execution Plan
------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cos
1 0 SORT (AGGREGATE)
2 1 INDEX (FULL SCAN) OF 'SYS_C003054‘
Note that in my tests, this access path is chosen when the table is very small, i.e. just a few blocks. For larger tables, CBO usually deemed the SORT step cheaper than accessing the index to get to the table.