Scanning only the last page of the table.
This message indicates that a query containing an ungrouped (scalar) max aggregate can access only the last page of the table to return the value.
Scanning only up to the first qualifying row.
This message appears only for queries that use an ungrouped (scalar) min aggregate. The aggregated column needs to be the leading column in the index.
For indexes with the leading key created in descending order, the use of the messages for min and max aggregates is reversed:
min uses “Positioning at index end”
while max prints “Positioning at index start” and “Scanning only up to the first qualifying row.”
See Performance and Tuning Guide: Optimizing and Abstract Plans for more information.