問題文
The utility turns the customer tariff table into a system-versioned temporal table so that any past state can be reconstructed. Six months later the history table is far larger than the team predicted, and storage cost is now a budget question. Which statement explains the growth and names the documented lever?
選択肢
- System versioning stores only the latest previous version of each row, so the size is bounded by the row count of the current table.
- The history table can be emptied at any time with a delete statement, so retention needs no design decision; a modification statement adds a row to history even when no column value actually changes, so the team can let history grow with the statement count and simply clear the rows they no longer need whenever storage cost becomes a budget question.
- Only rows whose values changed are written to history, so the growth must come from the period columns being stored twice per row.
- A modification statement adds a row to the history table even when no column value actually changes, so history grows with the number of statements rather than with the number of real changes; the documented lever is to manage the retention of the historical data.