APL - PCC BucketData Support - Buckets
- Kevin Wu
The BucketData APL functions are used for managing the storage of bucket data objects.
The BucketData Support functions include:
pccBeginBucketDataTransaction
Creates a transaction object that can be called when using transaction lock.
any pccBeginBucketDataTransaction()
Parameters
| Parameter | Description |
|---|---|
Returns: | A transaction object. |
Example
any myTransaction = pccBeginBucketDataTransaction ();
will create a transaction object named myTransaction .
pccBucketDataLookup
Retrieves the BucketDataHolder object with the stated key from storage.
BucketDataHolder pccBucketDataLookup( string key, any txn )
Parameters
| Parameter | Description |
|---|---|
| The key that uniquely identifies the |
| States the transaction object to be used when using transaction lock. If transaction lock is not used, this parameter should be set to |
Returns: | The |
Example
pccBucketDataLookup ("555", myTransaction);
will retrieve a BucketDataHolder object with key 555 from storage and apply transaction lock with the transaction object myTransaction .
pccBucketDataLookupMany
Retrieves a number of BucketDataHolder objects included in the stated list from storage.
map<string, BucketDataHolder> pccBucketDataLookupMany ( list<string> keys, any txn )
Parameters
| Parameter | Description |
|---|---|
| The list of keys that uniquely identify the |
| States the transaction object to be used when using transaction lock. If transaction lock is not used, this parameter should be set to |
Returns: | The |
Example
pccBucketDataLookupMany(myList, myTransaction);
will retrieve the BucketDataHolder objects stated in the myList list from storage and apply transaction lock with the transaction object myTransaction .
pccBucketDataStore
Stores the BucketDataHolder object to storage.
boolean pccBucketDataStore ( string key, BucketDataHolder bdh, any txn [, boolean throwException, int expiration] )
To avoid race conditions during the creation of a new bucket data holder object it is recommended to use a transaction object. If it is not used and there are two parallel requests for object creation, the second request will overwrite the first.
Parameters
| Parameter | Description |
|---|---|
| The key that uniquely identifies the |
| The |
| States the transaction object to be used when using transaction lock. If a transaction without a lock is used, this parameter should be set to |
| An optional parameter that can be set to false to be able to handle any storage errors. In this case the return value has to be checked and the |
expiration | An optional parameter that can be set to an integer value in seconds. This value is the TTL (Time-To-Live) for the BucketDataHolder object passed along with it. This parameter is only supported for Couchbase data store, versions 5.5 and above. Note! If you use the If the If transaction ( |
Returns: | True if the operation succeeded. This will always be the case unless |
Example
pccBucketDataStore("777", myBucket, myTransaction, true, 60);
In the case of using a Couchbase data store, the above function stores the myBucket BucketDataHolder object with 60 seconds TTL and key 777, while adding the BucketDataHolder object into the transaction object myTransaction.
In the case of any other data store, the above function stores the myBucket BucketDataHolder object with key 777, while adding the BucketDataHolder object into the transaction object myTransaction.
pccCommitBucketDataTransaction
Commits the changes that have been made to the BucketDataHolder objects that are using the stated transaction object.
void pccCommitBucketDataTransaction( any txn )
Parameters
| Parameter | Description |
|---|---|
| The transaction object for which changes should be committed. |
Example
pccCommitBucketDataTransaction (myTransaction);
will commit the changes made to the BucketDataHolder objects using the myTransaction transaction object.
pccRollbackBucketDataTransaction
Removes any changes that have been made to the BucketDataHolder objects that are using the stated transaction object.
void pccRollbackBucketDataTransaction( any txn )
Parameters
| Parameter | Description |
|---|---|
| The transaction object for which changes should be rolled back. |
Example
pccRollbackBucketDataTransaction (myTransaction);
will rollback the changes made to the BucketDataHolder objects using the myTransaction transaction object.
pccBucketDataRemove
Removes a BucketDataHolder object from storage.
void pccBucketDataRemove( string key, any txn )
Parameters
| Parameter | Description |
|---|---|
| The key that uniquely identifies the |
| The transaction when transaction lock is used. |
Example
pccBucketDataRemove ("754", myTransaction);
will remove the BucketDataHolder object with key 754> from storage and apply transaction lock with the transaction object >myTransaction .
pccCreateBucketDataKeyIterator
Creates an iterator which is used for moving from key to key in the database.
any pccCreateBucketDataKeyIterator( [string startKey [, string stopKey]] )
Parameters
| Parameter | Description |
|---|---|
| Optional parameter for stating which key to start with. This key will also be included. |
| Optional parameter for stating which key to end with. This key will also be included. |
Returns: | The iterator that has been created. |
Example
any myIterator = pccCreateBucketDataKeyIterator( );
will create an iterator named myIterator .
pccDestroyBucketDataKeyIterator
Removes the stated iterator and returns all the resources that are being used.
void pccDestroyBucketDataKeyIterator( any iterator )
Parameters
| Parameter | Description |
|---|---|
| The iterator you want to remove. |
Example
pccDestroyBucketDataKeyIterator(myIterator);
will remove the iterator named myIterator .
pccHasNextBucketDataKey
Asks the iterator if there are more keys to retrieve.
boolean pccHasNextBucketDataKey( any iterator )
Parameters
| Parameter | Description |
|---|---|
| The iterator you want to ask. |
Returns: | Information whether there is more data to retrieve or not. If true is returned, there is more data to be retrieved with the pccGetNextBucketDataKey function. If false is returned, there is no more data and the function pccGetNextBucketDataKey should not be called again. |
Example
pccDestroyBucketDataKeyIterator(myIterator);
will return the next key from the iterator named myIterator if the iterator has next key.
pccGetNextBucketDataKey
Retrieves the next key from the iterator.
string pccGetNextBucketDataKey( any iterator )
Parameters
| Parameter | Description |
|---|---|
| The iterator you want to retrieve the key from. |
Returns: | The next key, or null if no more keys are available. |
Example
string key = pccGetNextBucketDataKey(myIterator);
will return the next key from the iterator named myIterator .
pccGetNextBucketDataKeys
Retrieves several keys from the iterator.
list<string> pccGetNextBucketDataKeys( any iterator [, int count] )
Parameters
| Parameter | Description |
|---|---|
| The iterator you want to retrieve the keys from. |
| Optional parameter for controlling the maximum number of keys to retrieve. |
Returns: | A list containing the retrieved keys. |
Example
list<string> keys = pccGetNextBucketDataKeys(myIterator, 5);
will return a list of maximum 5 keys with the name keys from the iterator named myIterator .