DROP TABLE IF EXISTS expdata;

CREATE TABLE expdata ( id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, 
value FLOAT,
INDEX log10_fi ((log10(value)))
);

INSERT INTO expdata (value) VALUES (.01),(.1),(1),(10),(100);
SELECT id, value, log10(value) FROM expdata;

EXPLAIN SELECT * FROM expdata WHERE log10(value) < 0;
EXPLAIN SELECT * FROM expdata WHERE log10(value) = 0;

# Maybe log10(FLOAT) is not determenistic?
# Let's try with DECIMAL
DROP TABLE expdata;
CREATE TABLE expdata ( id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, 
value DECIMAL (10, 2),
INDEX log10_fi ((log10(value)))
);

INSERT INTO expdata (value) VALUES (.01),(.1),(1),(10),(100);
SELECT id, value, log10(value) FROM expdata;

EXPLAIN SELECT * FROM expdata WHERE log10(value) < 0;
EXPLAIN SELECT * FROM expdata WHERE log10(value) = 0;

DROP TABLE expdata;