exact: Exact Matching
matched-value: Value for exact match
exact matcher compares arbitrary key values
for exact equality.
Rows are considered to match only if the values in their
matched-value columns are exactly the same.
These values can be strings, numbers, or anything else.
A blank value never matches, not even with another blank one.
params parameter holds no values,
it does not have to be specified.
Note that the values must also be of the same type, so for instance
a Long (64-bit) integer value will not match an Integer (32-bit) value.