Phantoms
Preventing phantoms
3) Index locking
- If the query is implemented by SelectIndex(employee_dept_idx, dept = 'sales'),
then we can lock the corresponding B-tree pages.
- The insert from T2 would have to lock the page for insert.
- A lock conflict prevents the phantom.
- But this doesn't work if the query plan does not involve the
search of an index.
4) Prevent insertions while the query runs
- Not quite as bad as locking the entire table, but it's bad.
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