Class ScanRequest
- java.lang.Object
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- software.amazon.awssdk.core.SdkRequest
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- software.amazon.awssdk.awscore.AwsRequest
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- software.amazon.awssdk.services.dynamodb.model.DynamoDbRequest
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- software.amazon.awssdk.services.dynamodb.model.ScanRequest
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- All Implemented Interfaces:
SdkPojo,ToCopyableBuilder<ScanRequest.Builder,ScanRequest>
@Generated("software.amazon.awssdk:codegen") public final class ScanRequest extends DynamoDbRequest implements ToCopyableBuilder<ScanRequest.Builder,ScanRequest>
Represents the input of a
Scanoperation.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static interfaceScanRequest.Builder
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description List<String>attributesToGet()This is a legacy parameter.static ScanRequest.Builderbuilder()ConditionalOperatorconditionalOperator()This is a legacy parameter.StringconditionalOperatorAsString()This is a legacy parameter.BooleanconsistentRead()A Boolean value that determines the read consistency model during the scan:booleanequals(Object obj)booleanequalsBySdkFields(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.StringfilterExpression()A string that contains conditions that DynamoDB applies after theScanoperation, but before the data is returned to you.<T> Optional<T>getValueForField(String fieldName, Class<T> clazz)booleanhasAttributesToGet()For responses, this returns true if the service returned a value for the AttributesToGet property.booleanhasExclusiveStartKey()For responses, this returns true if the service returned a value for the ExclusiveStartKey property.booleanhasExpressionAttributeNames()For responses, this returns true if the service returned a value for the ExpressionAttributeNames property.booleanhasExpressionAttributeValues()For responses, this returns true if the service returned a value for the ExpressionAttributeValues property.inthashCode()booleanhasScanFilter()For responses, this returns true if the service returned a value for the ScanFilter property.StringindexName()The name of a secondary index to scan.Integerlimit()The maximum number of items to evaluate (not necessarily the number of matching items).StringprojectionExpression()A string that identifies one or more attributes to retrieve from the specified table or index.ReturnConsumedCapacityreturnConsumedCapacity()Returns the value of the ReturnConsumedCapacity property for this object.StringreturnConsumedCapacityAsString()Returns the value of the ReturnConsumedCapacity property for this object.Map<String,Condition>scanFilter()This is a legacy parameter.Map<String,SdkField<?>>sdkFieldNameToField()List<SdkField<?>>sdkFields()Integersegment()For a parallelScanrequest,Segmentidentifies an individual segment to be scanned by an application worker.Selectselect()The attributes to be returned in the result.StringselectAsString()The attributes to be returned in the result.static Class<? extends ScanRequest.Builder>serializableBuilderClass()StringtableName()The name of the table containing the requested items or if you provideIndexName, the name of the table to which that index belongs.ScanRequest.BuildertoBuilder()StringtoString()Returns a string representation of this object.IntegertotalSegments()For a parallelScanrequest,TotalSegmentsrepresents the total number of segments into which theScanoperation will be divided.-
Methods inherited from class software.amazon.awssdk.awscore.AwsRequest
overrideConfiguration
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface software.amazon.awssdk.utils.builder.ToCopyableBuilder
copy
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Method Detail
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tableName
public final 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.You can also provide the Amazon Resource Name (ARN) of the table in this parameter.
- Returns:
- The name of the table containing the requested items or if you provide
IndexName, the name of the table to which that index belongs.You can also provide the Amazon Resource Name (ARN) of the table in this parameter.
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indexName
public final 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
IndexNameparameter, you must also provideTableName.- Returns:
- 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
IndexNameparameter, you must also provideTableName.
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hasAttributesToGet
public final boolean hasAttributesToGet()
For responses, this returns true if the service returned a value for the AttributesToGet property. This DOES NOT check that the value is non-empty (for which, you should check theisEmpty()method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.
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attributesToGet
public final List<String> attributesToGet()
This is a legacy parameter. Use
ProjectionExpressioninstead. 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.
This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the
hasAttributesToGet()method.- Returns:
- This is a legacy parameter. Use
ProjectionExpressioninstead. For more information, see AttributesToGet in the Amazon DynamoDB Developer Guide.
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limit
public final 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
LastEvaluatedKeyto 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 inLastEvaluatedKeyto apply in a subsequent operation to continue the operation. For more information, see Working with Queries in the Amazon DynamoDB Developer Guide.- Returns:
- 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
LastEvaluatedKeyto 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 inLastEvaluatedKeyto apply in a subsequent operation to continue the operation. For more information, see Working with Queries in the Amazon DynamoDB Developer Guide.
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select
public final 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.
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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 specifyingProjectionExpressionwithout 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 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
SelectnorProjectionExpressionare specified, DynamoDB defaults toALL_ATTRIBUTESwhen accessing a table, andALL_PROJECTED_ATTRIBUTESwhen accessing an index. You cannot use bothSelectandProjectionExpressiontogether in a single request, unless the value forSelectisSPECIFIC_ATTRIBUTES. (This usage is equivalent to specifyingProjectionExpressionwithout any value forSelect.)If you use the
ProjectionExpressionparameter, then the value forSelectcan only beSPECIFIC_ATTRIBUTES. Any other value forSelectwill return an error.If the service returns an enum value that is not available in the current SDK version,
selectwill returnSelect.UNKNOWN_TO_SDK_VERSION. The raw value returned by the service is available fromselectAsString().- Returns:
- 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.
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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 specifyingProjectionExpressionwithout 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 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
SelectnorProjectionExpressionare specified, DynamoDB defaults toALL_ATTRIBUTESwhen accessing a table, andALL_PROJECTED_ATTRIBUTESwhen accessing an index. You cannot use bothSelectandProjectionExpressiontogether in a single request, unless the value forSelectisSPECIFIC_ATTRIBUTES. (This usage is equivalent to specifyingProjectionExpressionwithout any value forSelect.)If you use the
ProjectionExpressionparameter, then the value forSelectcan only beSPECIFIC_ATTRIBUTES. Any other value forSelectwill return an error. -
- See Also:
Select
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selectAsString
public final 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.
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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 specifyingProjectionExpressionwithout 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 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
SelectnorProjectionExpressionare specified, DynamoDB defaults toALL_ATTRIBUTESwhen accessing a table, andALL_PROJECTED_ATTRIBUTESwhen accessing an index. You cannot use bothSelectandProjectionExpressiontogether in a single request, unless the value forSelectisSPECIFIC_ATTRIBUTES. (This usage is equivalent to specifyingProjectionExpressionwithout any value forSelect.)If you use the
ProjectionExpressionparameter, then the value forSelectcan only beSPECIFIC_ATTRIBUTES. Any other value forSelectwill return an error.If the service returns an enum value that is not available in the current SDK version,
selectwill returnSelect.UNKNOWN_TO_SDK_VERSION. The raw value returned by the service is available fromselectAsString().- Returns:
- 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.
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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 specifyingProjectionExpressionwithout 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 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
SelectnorProjectionExpressionare specified, DynamoDB defaults toALL_ATTRIBUTESwhen accessing a table, andALL_PROJECTED_ATTRIBUTESwhen accessing an index. You cannot use bothSelectandProjectionExpressiontogether in a single request, unless the value forSelectisSPECIFIC_ATTRIBUTES. (This usage is equivalent to specifyingProjectionExpressionwithout any value forSelect.)If you use the
ProjectionExpressionparameter, then the value forSelectcan only beSPECIFIC_ATTRIBUTES. Any other value forSelectwill return an error. -
- See Also:
Select
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hasScanFilter
public final boolean hasScanFilter()
For responses, this returns true if the service returned a value for the ScanFilter property. This DOES NOT check that the value is non-empty (for which, you should check theisEmpty()method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.
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scanFilter
public final Map<String,Condition> scanFilter()
This is a legacy parameter. Use
FilterExpressioninstead. 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.
This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the
hasScanFilter()method.- Returns:
- This is a legacy parameter. Use
FilterExpressioninstead. For more information, see ScanFilter in the Amazon DynamoDB Developer Guide.
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conditionalOperator
public final ConditionalOperator conditionalOperator()
This is a legacy parameter. Use
FilterExpressioninstead. 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,
conditionalOperatorwill returnConditionalOperator.UNKNOWN_TO_SDK_VERSION. The raw value returned by the service is available fromconditionalOperatorAsString().- Returns:
- This is a legacy parameter. Use
FilterExpressioninstead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide. - See Also:
ConditionalOperator
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conditionalOperatorAsString
public final String conditionalOperatorAsString()
This is a legacy parameter. Use
FilterExpressioninstead. 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,
conditionalOperatorwill returnConditionalOperator.UNKNOWN_TO_SDK_VERSION. The raw value returned by the service is available fromconditionalOperatorAsString().- Returns:
- This is a legacy parameter. Use
FilterExpressioninstead. For more information, see ConditionalOperator in the Amazon DynamoDB Developer Guide. - See Also:
ConditionalOperator
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hasExclusiveStartKey
public final boolean hasExclusiveStartKey()
For responses, this returns true if the service returned a value for the ExclusiveStartKey property. This DOES NOT check that the value is non-empty (for which, you should check theisEmpty()method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.
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exclusiveStartKey
public final Map<String,AttributeValue> exclusiveStartKey()
The primary key of the first item that this operation will evaluate. Use the value that was returned for
LastEvaluatedKeyin the previous operation.The data type for
ExclusiveStartKeymust be String, Number or Binary. No set data types are allowed.In a parallel scan, a
Scanrequest that includesExclusiveStartKeymust specify the same segment whose previousScanreturned the corresponding value ofLastEvaluatedKey.Attempts to modify the collection returned by this method will result in an UnsupportedOperationException.
This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the
hasExclusiveStartKey()method.- Returns:
- The primary key of the first item that this operation will evaluate. Use the value that was returned for
LastEvaluatedKeyin the previous operation.The data type for
ExclusiveStartKeymust be String, Number or Binary. No set data types are allowed.In a parallel scan, a
Scanrequest that includesExclusiveStartKeymust specify the same segment whose previousScanreturned the corresponding value ofLastEvaluatedKey.
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returnConsumedCapacity
public final ReturnConsumedCapacity returnConsumedCapacity()
Returns the value of the ReturnConsumedCapacity property for this object.If the service returns an enum value that is not available in the current SDK version,
returnConsumedCapacitywill returnReturnConsumedCapacity.UNKNOWN_TO_SDK_VERSION. The raw value returned by the service is available fromreturnConsumedCapacityAsString().- Returns:
- The value of the ReturnConsumedCapacity property for this object.
- See Also:
ReturnConsumedCapacity
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returnConsumedCapacityAsString
public final String returnConsumedCapacityAsString()
Returns the value of the ReturnConsumedCapacity property for this object.If the service returns an enum value that is not available in the current SDK version,
returnConsumedCapacitywill returnReturnConsumedCapacity.UNKNOWN_TO_SDK_VERSION. The raw value returned by the service is available fromreturnConsumedCapacityAsString().- Returns:
- The value of the ReturnConsumedCapacity property for this object.
- See Also:
ReturnConsumedCapacity
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totalSegments
public final Integer totalSegments()
For a parallel
Scanrequest,TotalSegmentsrepresents the total number of segments into which theScanoperation will be divided. The value ofTotalSegmentscorresponds 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 aTotalSegmentsvalue of 4.The value for
TotalSegmentsmust be greater than or equal to 1, and less than or equal to 1000000. If you specify aTotalSegmentsvalue of 1, theScanoperation will be sequential rather than parallel.If you specify
TotalSegments, you must also specifySegment.- Returns:
- For a parallel
Scanrequest,TotalSegmentsrepresents the total number of segments into which theScanoperation will be divided. The value ofTotalSegmentscorresponds 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 aTotalSegmentsvalue of 4.The value for
TotalSegmentsmust be greater than or equal to 1, and less than or equal to 1000000. If you specify aTotalSegmentsvalue of 1, theScanoperation will be sequential rather than parallel.If you specify
TotalSegments, you must also specifySegment.
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segment
public final Integer segment()
For a parallel
Scanrequest,Segmentidentifies 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
Segmentvalue of 0, the second thread specifies 1, and so on.The value of
LastEvaluatedKeyreturned from a parallelScanrequest must be used asExclusiveStartKeywith the same segment ID in a subsequentScanoperation.The value for
Segmentmust be greater than or equal to 0, and less than the value provided forTotalSegments.If you provide
Segment, you must also provideTotalSegments.- Returns:
- For a parallel
Scanrequest,Segmentidentifies 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
Segmentvalue of 0, the second thread specifies 1, and so on.The value of
LastEvaluatedKeyreturned from a parallelScanrequest must be used asExclusiveStartKeywith the same segment ID in a subsequentScanoperation.The value for
Segmentmust be greater than or equal to 0, and less than the value provided forTotalSegments.If you provide
Segment, you must also provideTotalSegments.
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projectionExpression
public final 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.
- Returns:
- 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.
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filterExpression
public final String filterExpression()
A string that contains conditions that DynamoDB applies after the
Scanoperation, but before the data is returned to you. Items that do not satisfy theFilterExpressioncriteria are not returned.A
FilterExpressionis 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.
- Returns:
- A string that contains conditions that DynamoDB applies after the
Scanoperation, but before the data is returned to you. Items that do not satisfy theFilterExpressioncriteria are not returned.A
FilterExpressionis 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.
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hasExpressionAttributeNames
public final boolean hasExpressionAttributeNames()
For responses, this returns true if the service returned a value for the ExpressionAttributeNames property. This DOES NOT check that the value is non-empty (for which, you should check theisEmpty()method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.
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expressionAttributeNames
public final 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.
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To create a placeholder for repeating occurrences of an attribute name in an expression.
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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:
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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:
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#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.
This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the
hasExpressionAttributeNames()method.- Returns:
- 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.
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To create a placeholder for repeating occurrences of an attribute name in an expression.
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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:
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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:
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#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.
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hasExpressionAttributeValues
public final boolean hasExpressionAttributeValues()
For responses, this returns true if the service returned a value for the ExpressionAttributeValues property. This DOES NOT check that the value is non-empty (for which, you should check theisEmpty()method on the property). This is useful because the SDK will never return a null collection or map, but you may need to differentiate between the service returning nothing (or null) and the service returning an empty collection or map. For requests, this returns true if a value for the property was specified in the request builder, and false if a value was not specified.
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expressionAttributeValues
public final 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
ProductStatusattribute was one of the following:Available | Backordered | DiscontinuedYou would first need to specify
ExpressionAttributeValuesas 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.
This method will never return null. If you would like to know whether the service returned this field (so that you can differentiate between null and empty), you can use the
hasExpressionAttributeValues()method.- Returns:
- 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
ProductStatusattribute was one of the following:Available | Backordered | DiscontinuedYou would first need to specify
ExpressionAttributeValuesas 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.
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consistentRead
public final Boolean consistentRead()
A Boolean value that determines the read consistency model during the scan:
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If
ConsistentReadisfalse, then the data returned fromScanmight not contain the results from other recently completed write operations (PutItem,UpdateItem, orDeleteItem). -
If
ConsistentReadistrue, then all of the write operations that completed before theScanbegan are guaranteed to be contained in theScanresponse.
The default setting for
ConsistentReadisfalse.The
ConsistentReadparameter is not supported on global secondary indexes. If you scan a global secondary index withConsistentReadset to true, you will receive aValidationException.- Returns:
- A Boolean value that determines the read consistency model during the scan:
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If
ConsistentReadisfalse, then the data returned fromScanmight not contain the results from other recently completed write operations (PutItem,UpdateItem, orDeleteItem). -
If
ConsistentReadistrue, then all of the write operations that completed before theScanbegan are guaranteed to be contained in theScanresponse.
The default setting for
ConsistentReadisfalse.The
ConsistentReadparameter is not supported on global secondary indexes. If you scan a global secondary index withConsistentReadset to true, you will receive aValidationException. -
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toBuilder
public ScanRequest.Builder toBuilder()
- Specified by:
toBuilderin interfaceToCopyableBuilder<ScanRequest.Builder,ScanRequest>- Specified by:
toBuilderin classDynamoDbRequest
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builder
public static ScanRequest.Builder builder()
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serializableBuilderClass
public static Class<? extends ScanRequest.Builder> serializableBuilderClass()
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hashCode
public final int hashCode()
- Overrides:
hashCodein classAwsRequest
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equals
public final boolean equals(Object obj)
- Overrides:
equalsin classAwsRequest
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equalsBySdkFields
public final boolean equalsBySdkFields(Object obj)
- Specified by:
equalsBySdkFieldsin interfaceSdkPojo
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toString
public final String toString()
Returns a string representation of this object. This is useful for testing and debugging. Sensitive data will be redacted from this string using a placeholder value.
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getValueForField
public final <T> Optional<T> getValueForField(String fieldName, Class<T> clazz)
- Overrides:
getValueForFieldin classSdkRequest
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sdkFieldNameToField
public final Map<String,SdkField<?>> sdkFieldNameToField()
- Specified by:
sdkFieldNameToFieldin interfaceSdkPojo
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