If you want to retrieve all the records that match only some of
the major key components, use
KVStore.storeIterator(). Using this
method, you can iterate over all of the records in the store,
or over all of the records that match a partial set of major
components.
KVStore.storeIterator() does not
return the entire set of records all at once. Instead, it
batches the fetching of key-value pairs in the iterator, to
minimize the number of network round trips, while not
monopolizing the available bandwidth. Also, the records
returned by this method are in unsorted order.
Note that this method does not result in a single atomic operation. Because the retrieval is batched, the return set can change over the course of the entire retrieval operation. As a result, you lose the atomicity of the operation when you use this method.
This method provides for an unsorted traversal of records in the store. If you do not provide a key, then this method will iterate over all of the records in the store. If you do provide a key, you must provide only a subset of the major key components used by your records. The key that you provide must NOT include any minor key components.
To use this method, you must specify:
A traversal direction.
The suggested number of keys to fetch during each network round trip. If you provide a value of 0, an internally determined default is used.
For example, suppose you are storing user records that use keys like this:
/Smith/Bob/-/birthdate /Smith/Bob/-/phonenumber /Smith/Bob/-/image /Smith/Bob/-/userID /Smith/Patricia/-/birthdate /Smith/Patricia/-/phonenumber /Smith/Patricia/-/image /Smith/Patricia/-/userID /Smith/Richard/-/birthdate /Smith/Richard/-/phonenumber /Smith/Richard/-/image /Smith/Richard/-/userID /Wong/Bill/-/birthdate /Wong/Bill/-/phonenumber /Wong/Bill/-/image /Wong/Bill/-/userID
Then you can retrieve all of the records for all users whose surname is 'Smith' as follows:
package kvstore.basicExample;
...
import oracle.kv.Direction;
import oracle.kv.Key;
import oracle.kv.Value;
import oracle.kv.KeyValueVersion;
import java.util.ArrayList;
import java.util.Iterator;
...
ArrayList<String> majorComponents = new ArrayList<String>();
...
// Define the major and minor path components for the key
majorComponents.add("Smith");
// Create the retrieval key
Key myKey = Key.createKey(majorComponents);
// Now retrieve the records. Note that we do not show the creation of
// the kvstore handle here.
Iterator <KeyValueVersion>i =
kvstore.storeIterator(Direction.UNORDERED, 0,
myKey, null, null);
while (i.hasNext()) {
Value v = i.next().getValue();
// Do some work with the Value here
}