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struct es_mbm is an opaque data structure representing a membership filter. A membership filter is used by iterators ( struct es_mbi ) and sorted iterators ( struct es_mbs ) to traverse only those rows in a database node that meet some filtering criteria.

Membership filters can be applied to one or more integer database fields. The filter itself is a set of valid (or invalid) integer values that a database field may (or may not) have. Filters are bound to a specific field via es_mbb_mbm() and are used with the following combinations of iterator functions:

Membership filters are most effective for database fields with a tight range of values, such as date-ids or string-ids.
es_mbm_new Construct a new membership filter.
es_mbm_delete Delete a membership filter.
es_mbm_add Add a value to a membership filter.
es_mbm_addrange Add a range of values to a membership filter.

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