This shows the selectivities for a search clause on the title column, when an index exists for the column:
Estimated selectivity for title, selectivity = 0.001077, upper limit = 0.060200.
For equality search arguments where the value falls in a range cell:
The selectivity is the “Range cell density” displayed by optdiag.
The upper limit is the weight of the histogram cell.
If the value matches a frequency cell, the selectivity and upper limit are the weight of that cell.
For range queries, the upper limit is the sum of the weights of all histogram cells that contain values in the range. The upper limit is used only in cases where interpolation yields a selectivity that is greater than the upper limit.
The upper limit is not printed when the selectivity for a search argument is 1.
For join clauses, the selectivity is the “Total density” displayed by optdiag.