Is there any efficient way to delete all the items from a amazon dynamodb tabe at once.I have gone through the aws docs but there it's shown deletion of a single item.
You will want to use BatchWriteItem if you can't drop the table. If all your entries are within a single HashKey, you can use the Query API to retrieve the records, and then delete them 25 items at a time. If not, you'll probably have to Scan.
Alternatively, you could provide a simple wrapper around AmazonDynamoDBClient (from the official SDK) that collects a Set of Hash/Range keys that exist in your table. Then you wouldn't need to Query or Scan for the items you inserted after the test, since you would already have the Set built. That would look something like this:
public class KeyCollectingAmazonDynamoDB implements AmazonDynamoDB
{
private final AmazonDynamoDB delegate;
// HashRangePair is something you have to define
private final Set<Key> contents;
public InsertGatheringAmazonDynamoDB( AmazonDynamoDB delegate )
{
this.delegate = delegate;
this.contents = new HashSet<>();
}
@Override
public PutItemResult putItem( PutItemRequest putItemRequest )
throws AmazonServiceException, AmazonClientException
{
contents.add( extractKey( putItemRequest.getItem() ) );
return delegate.putItem( putItemRequest );
}
private Key extractKey( Map<String, AttributeValue> item )
{
// TODO Define your hash/range key extraction here
// Create a Key object
return new Key( hashKey, rangeKey );
}
@Override
public DeleteItemResult deleteItem( DeleteItemRequest deleteItemRequest )
throws AmazonServiceException, AmazonClientException
{
contents.remove( deleteItemRequest.getKey() );
return delegate.deleteItem( deleteItemRequest );
}
@Override
public BatchWriteItemResult batchWriteItem( BatchWriteItemRequest batchWriteItemRequest )
throws AmazonServiceException, AmazonClientException
{
// Similar extraction, but in bulk.
for ( Map.Entry<String, List<WriteRequest>> entry : batchWriteItemRequest.getRequestItems().entrySet() )
{
String tableName = entry.getKey();
List<WriteRequest> writeRequests = entry.getValue();
for ( WriteRequest writeRequest : writeRequests )
{
PutRequest putRequest = writeRequest.getPutRequest();
if ( putRequest != null )
{
// Add to Set just like putItem
}
DeleteRequest deleteRequest = writeRequest.getDeleteRequest();
if ( deleteRequest != null )
{
// Remove from Set just like deleteItem
}
}
}
// Write through to DynamoDB
return delegate.batchWriteItem( batchWriteItemRequest );
}
// remaining methods elided, since they're direct delegation
}
Key is a class within the DynamoDB SDK that accepts zero, one, or two AttributeValue objects in the constructor to represent a hash key or a hash/range key. Assuming it's equals and hashCode methods work, you can use in within the Set I described. If they don't, you'll have to write your own Key class.
This should get you a maintained Set for use within your tests. It's not specific to a table, so you might need to add another layer of collection if you're using multiple tables. That would change Set<Key> to something like Map<TableName, Set<Key>>. You would need to look at the getTableName() property to pick the correct Set to update.
Once your test finishes, grabbing the contents of the table and deleting should be straightforward.
One final suggestion: use a different table for testing than you do for your application. Create an identical schema, but give the table a different name. You probably even want a different IAM user to prevent your test code from accessing your production table. If you have questions about that, feel free to open a separate question for that scenario.
DynamoDBMapper will do the job in few lines :
AWSCredentials credentials = new PropertiesCredentials(credentialFile);
client = new AmazonDynamoDBClient(credentials);
DynamoDBMapper mapper = new DynamoDBMapper(this.client);
DynamoDBScanExpression scanExpression = new DynamoDBScanExpression();
PaginatedScanList<LogData> result = mapper.scan(LogData.class, scanExpression);
for (LogData data : result) {
mapper.delete(data);
}
Is there any efficient way to delete all the items from a amazon dynamodb tabe at once.I have gone through the aws docs but there it's shown deletion of a single item.
You will want to use BatchWriteItem if you can't drop the table. If all your entries are within a single HashKey, you can use the Query API to retrieve the records, and then delete them 25 items at a time. If not, you'll probably have to Scan.
Alternatively, you could provide a simple wrapper around AmazonDynamoDBClient (from the official SDK) that collects a Set of Hash/Range keys that exist in your table. Then you wouldn't need to Query or Scan for the items you inserted after the test, since you would already have the Set built. That would look something like this:
public class KeyCollectingAmazonDynamoDB implements AmazonDynamoDB
{
private final AmazonDynamoDB delegate;
// HashRangePair is something you have to define
private final Set<Key> contents;
public InsertGatheringAmazonDynamoDB( AmazonDynamoDB delegate )
{
this.delegate = delegate;
this.contents = new HashSet<>();
}
@Override
public PutItemResult putItem( PutItemRequest putItemRequest )
throws AmazonServiceException, AmazonClientException
{
contents.add( extractKey( putItemRequest.getItem() ) );
return delegate.putItem( putItemRequest );
}
private Key extractKey( Map<String, AttributeValue> item )
{
// TODO Define your hash/range key extraction here
// Create a Key object
return new Key( hashKey, rangeKey );
}
@Override
public DeleteItemResult deleteItem( DeleteItemRequest deleteItemRequest )
throws AmazonServiceException, AmazonClientException
{
contents.remove( deleteItemRequest.getKey() );
return delegate.deleteItem( deleteItemRequest );
}
@Override
public BatchWriteItemResult batchWriteItem( BatchWriteItemRequest batchWriteItemRequest )
throws AmazonServiceException, AmazonClientException
{
// Similar extraction, but in bulk.
for ( Map.Entry<String, List<WriteRequest>> entry : batchWriteItemRequest.getRequestItems().entrySet() )
{
String tableName = entry.getKey();
List<WriteRequest> writeRequests = entry.getValue();
for ( WriteRequest writeRequest : writeRequests )
{
PutRequest putRequest = writeRequest.getPutRequest();
if ( putRequest != null )
{
// Add to Set just like putItem
}
DeleteRequest deleteRequest = writeRequest.getDeleteRequest();
if ( deleteRequest != null )
{
// Remove from Set just like deleteItem
}
}
}
// Write through to DynamoDB
return delegate.batchWriteItem( batchWriteItemRequest );
}
// remaining methods elided, since they're direct delegation
}
Key is a class within the DynamoDB SDK that accepts zero, one, or two AttributeValue objects in the constructor to represent a hash key or a hash/range key. Assuming it's equals and hashCode methods work, you can use in within the Set I described. If they don't, you'll have to write your own Key class.
This should get you a maintained Set for use within your tests. It's not specific to a table, so you might need to add another layer of collection if you're using multiple tables. That would change Set<Key> to something like Map<TableName, Set<Key>>. You would need to look at the getTableName() property to pick the correct Set to update.
Once your test finishes, grabbing the contents of the table and deleting should be straightforward.
One final suggestion: use a different table for testing than you do for your application. Create an identical schema, but give the table a different name. You probably even want a different IAM user to prevent your test code from accessing your production table. If you have questions about that, feel free to open a separate question for that scenario.
DynamoDBMapper will do the job in few lines :
AWSCredentials credentials = new PropertiesCredentials(credentialFile);
client = new AmazonDynamoDBClient(credentials);
DynamoDBMapper mapper = new DynamoDBMapper(this.client);
DynamoDBScanExpression scanExpression = new DynamoDBScanExpression();
PaginatedScanList<LogData> result = mapper.scan(LogData.class, scanExpression);
for (LogData data : result) {
mapper.delete(data);
}
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