@Generated(value="software.amazon.awssdk:codegen") public final class ScanRequest extends DynamoDbRequest implements ToCopyableBuilder<ScanRequest.Builder,ScanRequest>
Represents the input of a Scan
operation.
Modifier and Type | Class and Description |
---|---|
static interface |
ScanRequest.Builder |
Modifier and Type | Method and Description |
---|---|
List<String> |
attributesToGet()
This is a legacy parameter.
|
static ScanRequest.Builder |
builder() |
ConditionalOperator |
conditionalOperator()
This is a legacy parameter.
|
String |
conditionalOperatorAsString()
This is a legacy parameter.
|
Boolean |
consistentRead()
A Boolean value that determines the read consistency model during the scan:
|
boolean |
equals(Object obj) |
boolean |
equalsBySdkFields(Object obj) |
Map<String,AttributeValue> |
exclusiveStartKey()
The primary key of the first item that this operation will evaluate.
|
Map<String,String> |
expressionAttributeNames()
One or more substitution tokens for attribute names in an expression.
|
Map<String,AttributeValue> |
expressionAttributeValues()
One or more values that can be substituted in an expression.
|
String |
filterExpression()
A string that contains conditions that DynamoDB applies after the
Scan operation, but before the
data is returned to you. |
<T> Optional<T> |
getValueForField(String fieldName,
Class<T> clazz) |
int |
hashCode() |
String |
indexName()
The name of a secondary index to scan.
|
Integer |
limit()
The maximum number of items to evaluate (not necessarily the number of matching items).
|
String |
projectionExpression()
A string that identifies one or more attributes to retrieve from the specified table or index.
|
ReturnConsumedCapacity |
returnConsumedCapacity()
Returns the value of the ReturnConsumedCapacity property for this object.
|
String |
returnConsumedCapacityAsString()
Returns the value of the ReturnConsumedCapacity property for this object.
|
Map<String,Condition> |
scanFilter()
This is a legacy parameter.
|
List<SdkField<?>> |
sdkFields() |
Integer |
segment()
For a parallel
Scan request, Segment identifies an individual segment to be scanned by
an application worker. |
Select |
select()
The attributes to be returned in the result.
|
String |
selectAsString()
The attributes to be returned in the result.
|
static Class<? extends ScanRequest.Builder> |
serializableBuilderClass() |
String |
tableName()
The name of the table containing the requested items; or, if you provide
IndexName , the name of the
table to which that index belongs. |
ScanRequest.Builder |
toBuilder() |
String |
toString()
Returns a string representation of this object.
|
Integer |
totalSegments()
For a parallel
Scan request, TotalSegments represents the total number of segments into
which the Scan operation will be divided. |
overrideConfiguration
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
copy
public String tableName()
The name of the table containing the requested items; or, if you provide IndexName
, the name of the
table to which that index belongs.
IndexName
, the name
of the table to which that index belongs.public String indexName()
The name of a secondary index to scan. This index can be any local secondary index or global secondary index.
Note that if you use the IndexName
parameter, you must also provide TableName
.
IndexName
parameter, you must also provide
TableName
.public List<String> attributesToGet()
This is a legacy parameter. Use ProjectionExpression
instead. For more information, see AttributesToGet in the Amazon DynamoDB Developer Guide.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
ProjectionExpression
instead. For more information, see AttributesToGet in the Amazon DynamoDB Developer Guide.public Integer limit()
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 Working with
Queries in the Amazon DynamoDB Developer Guide.
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 Working with
Queries in the Amazon DynamoDB Developer Guide.public Select select()
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 specifying ALL_ATTRIBUTES
.
COUNT
- Returns the number of matching items, rather than the matching items themselves.
SPECIFIC_ATTRIBUTES
- Returns only the attributes listed in AttributesToGet
. This
return value is equivalent to specifying AttributesToGet
without specifying any value for
Select
.
If you query or scan a local secondary index and request only attributes that are projected into that index, the operation reads 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 AttributesToGet
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 AttributesToGet
together in a single request,
unless the value for Select
is SPECIFIC_ATTRIBUTES
. (This usage is equivalent to
specifying AttributesToGet
without any value for Select
.)
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.
If the service returns an enum value that is not available in the current SDK version, select
will
return Select.UNKNOWN_TO_SDK_VERSION
. The raw value returned by the service is available from
selectAsString()
.
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 specifying ALL_ATTRIBUTES
.
COUNT
- Returns the number of matching items, rather than the matching items themselves.
SPECIFIC_ATTRIBUTES
- Returns only the attributes listed in AttributesToGet
.
This return value is equivalent to specifying AttributesToGet
without specifying any value
for Select
.
If you query or scan a local secondary index and request only attributes that are projected into that index, the operation reads 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 AttributesToGet
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 AttributesToGet
together in
a single request, unless the value for Select
is SPECIFIC_ATTRIBUTES
. (This
usage is equivalent to specifying AttributesToGet
without any value for Select
.)
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.
Select
public String selectAsString()
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 specifying ALL_ATTRIBUTES
.
COUNT
- Returns the number of matching items, rather than the matching items themselves.
SPECIFIC_ATTRIBUTES
- Returns only the attributes listed in AttributesToGet
. This
return value is equivalent to specifying AttributesToGet
without specifying any value for
Select
.
If you query or scan a local secondary index and request only attributes that are projected into that index, the operation reads 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 AttributesToGet
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 AttributesToGet
together in a single request,
unless the value for Select
is SPECIFIC_ATTRIBUTES
. (This usage is equivalent to
specifying AttributesToGet
without any value for Select
.)
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.
If the service returns an enum value that is not available in the current SDK version, select
will
return Select.UNKNOWN_TO_SDK_VERSION
. The raw value returned by the service is available from
selectAsString()
.
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 specifying ALL_ATTRIBUTES
.
COUNT
- Returns the number of matching items, rather than the matching items themselves.
SPECIFIC_ATTRIBUTES
- Returns only the attributes listed in AttributesToGet
.
This return value is equivalent to specifying AttributesToGet
without specifying any value
for Select
.
If you query or scan a local secondary index and request only attributes that are projected into that index, the operation reads 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 AttributesToGet
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 AttributesToGet
together in
a single request, unless the value for Select
is SPECIFIC_ATTRIBUTES
. (This
usage is equivalent to specifying AttributesToGet
without any value for Select
.)
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.
Select
public Map<String,Condition> scanFilter()
This is a legacy parameter. Use FilterExpression
instead. For more information, see ScanFilter in the Amazon DynamoDB Developer Guide.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
FilterExpression
instead. For more information, see ScanFilter in the Amazon DynamoDB Developer Guide.public ConditionalOperator conditionalOperator()
This is a legacy parameter. Use FilterExpression
instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.
If the service returns an enum value that is not available in the current SDK version,
conditionalOperator
will return ConditionalOperator.UNKNOWN_TO_SDK_VERSION
. The raw value
returned by the service is available from conditionalOperatorAsString()
.
FilterExpression
instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.ConditionalOperator
public String conditionalOperatorAsString()
This is a legacy parameter. Use FilterExpression
instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.
If the service returns an enum value that is not available in the current SDK version,
conditionalOperator
will return ConditionalOperator.UNKNOWN_TO_SDK_VERSION
. The raw value
returned by the service is available from conditionalOperatorAsString()
.
FilterExpression
instead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide.ConditionalOperator
public Map<String,AttributeValue> exclusiveStartKey()
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.
In a parallel scan, a Scan
request that includes ExclusiveStartKey
must specify the
same segment whose previous Scan
returned the corresponding value of LastEvaluatedKey
.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
LastEvaluatedKey
in the previous operation.
The data type for ExclusiveStartKey
must be String, Number or Binary. No set data types are
allowed.
In a parallel scan, a Scan
request that includes ExclusiveStartKey
must specify
the same segment whose previous Scan
returned the corresponding value of
LastEvaluatedKey
.
public ReturnConsumedCapacity returnConsumedCapacity()
If the service returns an enum value that is not available in the current SDK version,
returnConsumedCapacity
will return ReturnConsumedCapacity.UNKNOWN_TO_SDK_VERSION
. The raw value
returned by the service is available from returnConsumedCapacityAsString()
.
ReturnConsumedCapacity
public String returnConsumedCapacityAsString()
If the service returns an enum value that is not available in the current SDK version,
returnConsumedCapacity
will return ReturnConsumedCapacity.UNKNOWN_TO_SDK_VERSION
. The raw value
returned by the service is available from returnConsumedCapacityAsString()
.
ReturnConsumedCapacity
public Integer totalSegments()
For a parallel Scan
request, TotalSegments
represents the total number of segments into
which the Scan
operation will be divided. The value of TotalSegments
corresponds to the
number of application workers that will perform the parallel scan. For example, if you want to use four
application threads to scan a table or an index, specify a TotalSegments
value of 4.
The value for TotalSegments
must be greater than or equal to 1, and less than or equal to 1000000.
If you specify a TotalSegments
value of 1, the Scan
operation will be sequential rather
than parallel.
If you specify TotalSegments
, you must also specify Segment
.
Scan
request, TotalSegments
represents the total number of
segments into which the Scan
operation will be divided. The value of
TotalSegments
corresponds to the number of application workers that will perform the
parallel scan. For example, if you want to use four application threads to scan a table or an index,
specify a TotalSegments
value of 4.
The value for TotalSegments
must be greater than or equal to 1, and less than or equal to
1000000. If you specify a TotalSegments
value of 1, the Scan
operation will be
sequential rather than parallel.
If you specify TotalSegments
, you must also specify Segment
.
public Integer segment()
For a parallel Scan
request, Segment
identifies an individual segment to be scanned by
an application worker.
Segment IDs are zero-based, so the first segment is always 0. For example, if you want to use four application
threads to scan a table or an index, then the first thread specifies a Segment
value of 0, the
second thread specifies 1, and so on.
The value of LastEvaluatedKey
returned from a parallel Scan
request must be used as
ExclusiveStartKey
with the same segment ID in a subsequent Scan
operation.
The value for Segment
must be greater than or equal to 0, and less than the value provided for
TotalSegments
.
If you provide Segment
, you must also provide TotalSegments
.
Scan
request, Segment
identifies an individual segment to be
scanned by an application worker.
Segment IDs are zero-based, so the first segment is always 0. For example, if you want to use four
application threads to scan a table or an index, then the first thread specifies a Segment
value of 0, the second thread specifies 1, and so on.
The value of LastEvaluatedKey
returned from a parallel Scan
request must be
used as ExclusiveStartKey
with the same segment ID in a subsequent Scan
operation.
The value for Segment
must be greater than or equal to 0, and less than the value provided
for TotalSegments
.
If you provide Segment
, you must also provide TotalSegments
.
public String projectionExpression()
A string that identifies one or more attributes to retrieve from the specified table or index. 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 Specifying Item Attributes in the Amazon DynamoDB Developer Guide.
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 Specifying Item Attributes in the Amazon DynamoDB Developer Guide.
public String filterExpression()
A string that contains conditions that DynamoDB applies after the Scan
operation, but before the
data is returned to you. Items that do not satisfy the FilterExpression
criteria are not returned.
A FilterExpression
is applied after the items have already been read; the process of filtering does
not consume any additional read capacity units.
For more information, see Filter Expressions in the Amazon DynamoDB Developer Guide.
Scan
operation, but before
the data is returned to you. Items that do not satisfy the FilterExpression
criteria are not
returned.
A FilterExpression
is applied after the items have already been read; the process of
filtering does not consume any additional read capacity units.
For more information, see Filter Expressions in the Amazon DynamoDB Developer Guide.
public Map<String,String> expressionAttributeNames()
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:
#P = :val
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.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
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:
#P = :val
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.
public Map<String,AttributeValue> expressionAttributeValues()
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 Condition Expressions in the Amazon DynamoDB Developer Guide.
Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
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 Condition Expressions in the Amazon DynamoDB Developer Guide.
public Boolean consistentRead()
A Boolean value that determines the read consistency model during the scan:
If ConsistentRead
is false
, then the data returned from Scan
might not
contain the results from other recently completed write operations (PutItem
, UpdateItem
, or DeleteItem
).
If ConsistentRead
is true
, then all of the write operations that completed before the
Scan
began are guaranteed to be contained in the Scan
response.
The default setting for ConsistentRead
is false
.
The ConsistentRead
parameter is not supported on global secondary indexes. If you scan a global
secondary index with ConsistentRead
set to true, you will receive a ValidationException
.
If ConsistentRead
is false
, then the data returned from Scan
might
not contain the results from other recently completed write operations (PutItem
,
UpdateItem
, or DeleteItem
).
If ConsistentRead
is true
, then all of the write operations that completed
before the Scan
began are guaranteed to be contained in the Scan
response.
The default setting for ConsistentRead
is false
.
The ConsistentRead
parameter is not supported on global secondary indexes. If you scan a
global secondary index with ConsistentRead
set to true, you will receive a
ValidationException
.
public ScanRequest.Builder toBuilder()
toBuilder
in interface ToCopyableBuilder<ScanRequest.Builder,ScanRequest>
toBuilder
in class DynamoDbRequest
public static ScanRequest.Builder builder()
public static Class<? extends ScanRequest.Builder> serializableBuilderClass()
public int hashCode()
hashCode
in class AwsRequest
public boolean equals(Object obj)
equals
in class AwsRequest
public boolean equalsBySdkFields(Object obj)
equalsBySdkFields
in interface SdkPojo
public String toString()
public <T> Optional<T> getValueForField(String fieldName, Class<T> clazz)
getValueForField
in class SdkRequest
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