Postgresql 中文操作指南
Description
SPI_cursor_close 关闭先前创建的游标，并释放其门户存储。
SPI_cursor_close closes a previously created cursor and releases its portal storage.
在事务的末尾自动关闭所有打开的游标。 SPI_cursor_close 仅在希望更快释放资源时调用。
All open cursors are closed automatically at the end of a transaction. SPI_cursor_close need only be invoked if it is desirable to release resources sooner.