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You must provide the name of the partition key attribute and a single value for that
attribute. Query returns all items with that partition key value. Optionally,
you can provide a sort key attribute and use a comparison operator to refine the search
results.
Use the KeyConditionExpression parameter to provide a specific value for the
partition key. The Query operation will return all of the items from the table
or index with that partition key value. You can optionally narrow the scope of the
Query operation by specifying a sort key value and a comparison operator in
KeyConditionExpression. To further refine the Query results, you can
optionally provide a FilterExpression. A FilterExpression determines
which items within the results should be returned to you. All of the other results
are discarded.
A Query operation always returns a result set. If no matching items are found,
the result set will be empty. Queries that do not return results consume the minimum
number of read capacity units for that type of read operation.
DynamoDB calculates the number of read capacity units consumed based on item size,
not on the amount of data that is returned to an application. The number of capacity
units consumed will be the same whether you request all of the attributes (the default
behavior) or just some of them (using a projection expression). The number will also
be the same whether or not you use a FilterExpression.
Query results are always sorted by the sort key value. If the data type of
the sort key is Number, the results are returned in numeric order; otherwise, the
results are returned in order of UTF-8 bytes. By default, the sort order is ascending.
To reverse the order, set the ScanIndexForward parameter to false.
A single Query operation will read up to the maximum number of items set (if
using the Limit parameter) or a maximum of 1 MB of data and then apply any
filtering to the results using FilterExpression. If LastEvaluatedKey
is present in the response, you will need to paginate the result set. For more information,
see Paginating
the Results in the Amazon DynamoDB Developer Guide.
FilterExpression is applied after a Query finishes, but before the
results are returned. A FilterExpression cannot contain partition key or sort
key attributes. You need to specify those attributes in the KeyConditionExpression.
A Query operation can return an empty result set and a LastEvaluatedKey
if all the items read for the page of results are filtered out.
You can query a table, a local secondary index, or a global secondary index. For a
query on a table or on a local secondary index, you can set the ConsistentRead
parameter to true and obtain a strongly consistent result. Global secondary
indexes support eventually consistent reads only, so do not specify ConsistentRead
when querying a global secondary index.
This is an asynchronous operation using the standard naming convention for .NET 4.5 or higher. For .NET 3.5 the operation is implemented as a pair of methods using the standard naming convention of BeginQuery and EndQuery.
Namespace: Amazon.DynamoDBv2
Assembly: AWSSDK.DynamoDBv2.dll
Version: 3.x.y.z
public abstract Task<QueryResponse> QueryAsync( QueryRequest request, CancellationToken cancellationToken )
Container for the necessary parameters to execute the Query service method.
A cancellation token that can be used by other objects or threads to receive notice of cancellation.
| Exception | Condition |
|---|---|
| InternalServerErrorException | An error occurred on the server side. |
| ProvisionedThroughputExceededException | Your request rate is too high. The Amazon Web Services SDKs for DynamoDB automatically retry requests that receive this exception. Your request is eventually successful, unless your retry queue is too large to finish. Reduce the frequency of requests and use exponential backoff. For more information, go to Error Retries and Exponential Backoff in the Amazon DynamoDB Developer Guide. |
| RequestLimitExceededException | Throughput exceeds the current throughput quota for your account. Please contact Amazon Web Services Support to request a quota increase. |
| ResourceNotFoundException | The operation tried to access a nonexistent table or index. The resource might not be specified correctly, or its status might not be ACTIVE. |
.NET Core App:
Supported in: 3.1
.NET Standard:
Supported in: 2.0
.NET Framework:
Supported in: 4.5