Types of Conditions
•Fixed-fraction subsets,
unrelated to time, often restrictions based on non-event
reference data.
–E.g., “North American orders”,
“orders from May’s Diner”
–These conditions are usually combined
with some other condition(s) correlating to recent events,
else the query would eventually return very old rows unlikely
to be useful, and often would return far too many rows to
“digest,” and too many to perform well. Fix queries that don’t
make sense in light of this!
–Concatenated indexes can combine
the selectivity of time-related conditions and reference
data.