| A FilterBlockBuilder is used to construct all
| of the filters for a particular Table. It
| generates a single string which is stored as
| a special block in the Table.
|
| The sequence of calls to FilterBlockBuilder
| must match the regexp: (StartBlock
| AddKey*)* Finish
| Return a new filter policy that uses a bloom
| filter with approximately the specified number
| of bits per key. A good value for bits_per_key
| is 10, which yields a filter with ~ 1% false
| positive rate.
|
| Callers must delete the result after any
| database that is using the result has been
| closed.
|
| Note: if you are using a custom comparator that
| ignores some parts of the keys being compared,
| you must not use NewBloomFilterPolicy() and
| must provide your own FilterPolicy that also
| ignores the corresponding parts of the keys.
| For example, if the comparator ignores trailing
| spaces, it would be incorrect to use
| a FilterPolicy (like NewBloomFilterPolicy) that
| does not ignore trailing spaces in keys.