Re: Non deterministic functions

[KimSeong Loh]

If the EXPLAIN shows that the index with column headline_hash is used, then I guess the md5 expression should have been evaluated only once, otherwise it cannot make use of the index since evaluation for each rows will not guarantee a constant to use the index.

Try this
SELECT BENCHMARK(100,MD5(LEFT(?body,900)));
It will show how long it takes to evaluate the function for 100 times, adjust the number of times accordingly.