All resource usage tables have the same nonunique primary index of TheDate, TheTime, and NodeID columns.
The primary index is nonunique because:
- Of rows that will appear with the same timestamp during daylight savings time.
- Some tables have multiple rows per logging period.
- Rows that have duplicate timestamps can be distinguished by the GmtTime column.
Because the primary index is nonunique, all resource usage tables are created as MULTISET tables. This prevents the system from checking for duplicate rows.
For more information on MULTISET tables, see “CREATE TABLE (Table Kind Clause)” in SQL Data Definition Language or “Duplicate Rows in Tables” in SQL Fundamentals.