Index Of 2 States Official

| User | Read | Write | Delete | |------|------|-------|--------| | A | 1 | 1 | 0 | | B | 1 | 0 | 0 | | C | 0 | 1 | 1 |

Always verify that your domain truly has exactly two mutually exclusive, exhaustive states. Pitfall 3: Forgetting About NULLs In SQL, a boolean column can be TRUE, FALSE, or NULL. NULL is a third state! If you create an index on two states but allow NULLs, your index is incomplete. index of 2 states

class TwoStateIndex: def __init__(self, size): self.size = size self.bitmap = 0 # integer as bitset def set_state(self, index, state): """Set state: 0 or 1 at given index""" if state == 1: self.bitmap |= (1 << index) else: self.bitmap &= ~(1 << index) | User | Read | Write | Delete

def find_all_with_state(self, state=1): """Return list of indices where state matches""" indices = [] for i in range(self.size): if self.get_state(i) == state: indices.append(i) return indices If you create an index on two states

A B-tree index on a boolean column divides the data into exactly two branches. While functional, it doesn't leverage bitwise parallelism. A bitmap index is often 10x to 100x smaller and faster for read-heavy analytical queries.