- For each relation T
NCARD(T)
- the cardinality of relation TTCARD(T)
- the number of pages in the segment that hold tuples of relation T.P(T)
- the fraction of data pages in the segment that hold tuples of relation T.- P(T) = TCARD(T) / (no. of non-empty pages in the segment).
- For each index I on relation T
ICARD(I)
number of distinct keys in index ININDX(I)
the number of pages in index I
Additionaly we can store number of distinct values if relation is reltively small.
def: SQL query operating only on one relation e.g.SELECT * FROM people where age > 5
.
See the article