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Bulk Retrieval API |
#include <db_cxx.h>class DbMultipleDataIterator { public: DbMultipleDataIterator(const Dbt &dbt);
bool next(Dbt &data); };
class DbMultipleKeyDataIterator { public: DbMultipleKeyDataIterator(const Dbt &dbt);
bool next(Dbt &key, Dbt &data); };
class DbMultipleRecnoDataIterator { public: DbMultipleRecnoDataIterator(const Dbt &dbt);
bool next(db_recno_t &key, Dbt &data); };
If either of the DB_MULTIPLE or DB_MULTIPLE_KEY flags were specified to the Db::get or Dbc::get method, the data Dbt returned by those interfaces will refer to a buffer that is filled with data. Access to that data is through the following classes.
All instances of the bulk retrieval classes may be used only once, and to traverse the bulk retrieval buffer in the forward direction only. However, they are nondestructive, so multiple iterators can be instantiated and used on the same returned data Dbt.
The DbMultipleIterator is a shared package-private base class for the three types of bulk-return Iterator; it should never be instantiated directly, but it handles the functionality shared by its subclasses.
The DbMultipleDataIterator class is used to iterate through data returned using the DB_MULTIPLE flag from a database belonging to any access method.
The constructor takes the data Dbt returned by the call to Db::get or Dbc::get that used the DB_MULTIPLE flag.
The DbMultipleDataIterator.next method takes a Dbt that will be filled in with a reference to a buffer, a size, and an offset that together yield the next data item in the original bulk retrieval buffer.
The DbMultipleDataIterator.next method returns false if no more data are available, and true otherwise.
The DbMultipleKeyDataIterator class is used to iterate through data returned using the DB_MULTIPLE_KEY flag from a database belonging to the Btree or Hash access methods.
The constructor takes the data Dbt returned by the call to Db::get or Dbc::get that used the DB_MULTIPLE_KEY flag.
The DbMultipleKeyDataIterator.next method takes two Dbts, one for a key and one for a data item, that will each be filled in with a reference to a buffer, a size, and an offset that together yield the next key and data item in the original bulk retrieval buffer. The DbMultipleKeyDataIterator.next method returns false if no more data are available, and true otherwise.
The DbMultipleKeyDataIterator.next method returns false if no more data are available, and true otherwise.
This class is used to iterate through data returned using the DB_MULTIPLE_KEY flag from a database belonging to the Recno or Queue access methods.
The constructor takes the data Dbt returned by the call to Db::get or Dbc::get that used the DB_MULTIPLE_KEY flag.
The DbMultipleRecnoDataIterator.next method returns false if no more data are available, and true otherwise.
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