Is the time complexity of the Oracle MAX function O(1), O(log n) or O(n) with respect to the number of rows in a table?
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Is the time complexity of the Oracle MAX function O(1), O(log n) or O(n) with respect to the number of rows in a table?
If you have a B-tree index on the column then finding the maximum value is O(log(n)) because the answer will be the last (or first) row of the index. Values are stored in the deepest nodes of the B-tree which has a height O(log(n)).
Without an index it is O(n) because all rows must be read to determine the maximum value.
Note: The O(n) notation ignores constants but in the real world these constants cannot be ignored. The difference between reading from disk and reading from memory is several orders of magnitude. Accessing the first value of an index is likely to be performed mostly in RAM, whereas a full table scan of a huge table will need to read mostly from disk.