Выбор типа курсора

Choosing a cursor type depends on several variables that include:

• Size of the result set.
• Percentage of the data likely to be needed.
• Performance of the cursor open.
• Need for cursor operations, such as scrolling or positioned updates.
• Level of visibility to data modifications made by other users.

Rules for Choosing a Cursor Type

Some rules to follow when choosing a cursor type are:

• Basetable and forward-only cursors open faster than static or keyset-driven cursors. Internal temporary work tables must be built when static and keyset-driven cursors are opened, but they are not required for basetable and forward-only cursors.
• Static and keyset-driven cursors increase the usage of the temporary database. Static server cursors build the entire cursor in the temporary database. Keyset-driven cursors build the keyset in the temporary database.
• If the base table is retrieved as is, without any projection or selection, then a base table cursor is recommended because it has the least overhead.
• Static cursors consume the most resources because they duplicate the data.

См. также

Основные понятия

Типы курсоров
Курсоры и блокировка
Неявные преобразования курсора
Обновление курсоров, управляемых набором ключей

Справка и поддержка

Получение помощи по SQL Server Compact Edition