query - Boto3 1.34.74 documentation
IndexName (string) – The name of an index to query. This index can be any local secondary index or global secondary index on the table. Note that if you use the IndexName
parameter, you must also provide TableName.
Select (string) –
The attributes to be returned in the result. You can retrieve all item attributes, specific item attributes, the count of matching items, or in the case of an index, some or all of the attributes projected into the index.
ALL_ATTRIBUTES
- Returns all of the item attributes from the specified table or index. If you query a local secondary index, then for each matching item in the index, DynamoDB fetches the entire item from the parent table. If the index is configured to project all item attributes, then all of the data can be obtained from the local secondary index, and no fetching is required.ALL_PROJECTED_ATTRIBUTES
- Allowed only when querying an index. Retrieves all attributes that have been projected into the index. If the index is configured to project all attributes, this return value is equivalent to specifyingALL_ATTRIBUTES
.COUNT
- Returns the number of matching items, rather than the matching items themselves. Note that this uses the same quantity of read capacity units as getting the items, and is subject to the same item size calculations.SPECIFIC_ATTRIBUTES
- Returns only the attributes listed inProjectionExpression
. This return value is equivalent to specifyingProjectionExpression
without specifying any value forSelect
. If you query or scan a local secondary index and request only attributes that are projected into that index, the operation will read only the index and not the table. If any of the requested attributes are not projected into the local secondary index, DynamoDB fetches each of these attributes from the parent table. This extra fetching incurs additional throughput cost and latency. If you query or scan a global secondary index, you can only request attributes that are projected into the index. Global secondary index queries cannot fetch attributes from the parent table.
If neither Select
nor ProjectionExpression
are specified, DynamoDB defaults to ALL_ATTRIBUTES
when accessing a table, and ALL_PROJECTED_ATTRIBUTES
when accessing an index. You cannot use both Select
and ProjectionExpression
together in a single request, unless the value for Select
is SPECIFIC_ATTRIBUTES
. (This usage is equivalent to specifying ProjectionExpression
without any value for Select
.)
Note
If you use the ProjectionExpression
parameter, then the value for Select
can only be SPECIFIC_ATTRIBUTES
. Any other value for Select
will return an error.
AttributesToGet (list) –
This is a legacy parameter. Use ProjectionExpression
instead. For more information, see AttributesToGet in the Amazon DynamoDB Developer Guide.
(string) –
Limit (integer) – The maximum number of items to evaluate (not necessarily the number of matching items). If DynamoDB processes the number of items up to the limit while processing the results, it stops the operation and returns the matching values up to that point, and a key in LastEvaluatedKey
to apply in a subsequent operation, so that you can pick up where you left off. Also, if the processed dataset size exceeds 1 MB before DynamoDB reaches this limit, it stops the operation and returns the matching values up to the limit, and a key in LastEvaluatedKey
to apply in a subsequent operation to continue the operation. For more information, see Query and Scan in the Amazon DynamoDB Developer Guide.
ConsistentRead (boolean) –
Determines the read consistency model: If set to true
, then the operation uses strongly consistent reads; otherwise, the operation uses eventually consistent reads.
Strongly consistent reads are not supported on global secondary indexes. If you query a global secondary index with ConsistentRead
set to true
, you will receive a ValidationException
.
KeyConditions (dict) –
This is a legacy parameter. Use KeyConditionExpression
instead. For more information, see KeyConditions in the Amazon DynamoDB Developer Guide.
(string) –
QueryFilter (dict) –
This is a legacy parameter. Use FilterExpression
instead. For more information, see QueryFilter in the Amazon DynamoDB Developer Guide.
(string) –
ConditionalOperator (string) – This is a legacy parameter. Use FilterExpression
instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.
ScanIndexForward (boolean) –
Specifies the order for index traversal: If true
(default), the traversal is performed in ascending order; if false
, the traversal is performed in descending order.
Items with the same partition key value are stored in sorted order by sort key. If the sort key data type is Number, the results are stored in numeric order. For type String, the results are stored in order of UTF-8 bytes. For type Binary, DynamoDB treats each byte of the binary data as unsigned.
If ScanIndexForward
is true
, DynamoDB returns the results in the order in which they are stored (by sort key value). This is the default behavior. If ScanIndexForward
is false
, DynamoDB reads the results in reverse order by sort key value, and then returns the results to the client.
ExclusiveStartKey (dict) –
The primary key of the first item that this operation will evaluate. Use the value that was returned for LastEvaluatedKey
in the previous operation.
The data type for ExclusiveStartKey
must be String, Number, or Binary. No set data types are allowed.
(string) –
ReturnConsumedCapacity (string) –
Determines the level of detail about either provisioned or on-demand throughput consumption that is returned in the response:
INDEXES
- The response includes the aggregateConsumedCapacity
for the operation, together withConsumedCapacity
for each table and secondary index that was accessed. Note that some operations, such asGetItem
andBatchGetItem
, do not access any indexes at all. In these cases, specifyingINDEXES
will only returnConsumedCapacity
information for table(s).TOTAL
- The response includes only the aggregateConsumedCapacity
for the operation.NONE
- NoConsumedCapacity
details are included in the response.
ProjectionExpression (string) –
A string that identifies one or more attributes to retrieve from the table. These attributes can include scalars, sets, or elements of a JSON document. The attributes in the expression must be separated by commas.
If no attribute names are specified, then all attributes will be returned. If any of the requested attributes are not found, they will not appear in the result.
For more information, see Accessing Item Attributes in the Amazon DynamoDB Developer Guide.
FilterExpression (condition from boto3.dynamodb.conditions.Attr
method) – The condition(s) an attribute(s) must meet. Valid conditions are listed in the DynamoDB Reference Guide.
KeyConditionExpression (condition from boto3.dynamodb.conditions.Key
method) – The condition(s) a key(s) must meet. Valid conditions are listed in the DynamoDB Reference Guide.
ExpressionAttributeNames (dict) –
One or more substitution tokens for attribute names in an expression. The following are some use cases for using ExpressionAttributeNames
:
To access an attribute whose name conflicts with a DynamoDB reserved word.
To create a placeholder for repeating occurrences of an attribute name in an expression.
To prevent special characters in an attribute name from being misinterpreted in an expression.
Use the # character in an expression to dereference an attribute name. For example, consider the following attribute name:
Percentile
The name of this attribute conflicts with a reserved word, so it cannot be used directly in an expression. (For the complete list of reserved words, see Reserved Words in the Amazon DynamoDB Developer Guide). To work around this, you could specify the following for ExpressionAttributeNames
:
{"#P":"Percentile"}
You could then use this substitution in an expression, as in this example:
Note
Tokens that begin with the : character are expression attribute values, which are placeholders for the actual value at runtime.
For more information on expression attribute names, see Specifying Item Attributes in the Amazon DynamoDB Developer Guide.
(string) –
(string) –
ExpressionAttributeValues (dict) –
One or more values that can be substituted in an expression.
Use the : (colon) character in an expression to dereference an attribute value. For example, suppose that you wanted to check whether the value of the ProductStatus attribute was one of the following:
Available | Backordered | Discontinued
You would first need to specify ExpressionAttributeValues
as follows:
{ ":avail":{"S":"Available"}, ":back":{"S":"Backordered"}, ":disc":{"S":"Discontinued"} }
You could then use these values in an expression, such as this:
ProductStatus IN (:avail, :back, :disc)
For more information on expression attribute values, see Specifying Conditions in the Amazon DynamoDB Developer Guide.
(string) –
ncG1vNJzZmian6m8dHrAppizp56WxLR6wqikaK5hZLGwr9SmnKeskam2sLqOmqeiZ5yWwaa%2F02ipnp6Vp7Kvr8Roqp6qpp6wpr%2BOnbCnmZ2ksaN705qZpZ1fpsKmvthnn62lnA%3D%3D