GeminiDB Serverless Usage and Constraints

This section describes GeminiDB Serverless usage and constraints.

Usage Notes

Serverless is compatible with GeminiDB DynamoDB-Compatible API. APIs of GeminiDB DynamoDB-Compatible instances can be used to add, delete, and modify Serverless tables. Only DDL operations can be performed on the console.
The current version does not support TransactWriteItems and TransactGetItems.
The current version does not support the following on-demand backup APIs: CreateBackup, DescribeBackup, DeleteBackup, ListBackups, and RestoreTableFromBackup.
The table or index name cannot contain periods (.).
All DDL APIs are synchronous APIs.

Supported Expressions

ConditionExpression and FilterExpression of GeminiDB DynamoDB-Compatible API support the following function syntax:

function ::=
    attribute_exists (path)
    | attribute_not_exists (path)
    | attribute_type (path, type)
    | begins_with (path, substr)
    | contains (path, operand)
operand in contains(path,operand) can only be an attribute value (that is, the value placeholder).

UpdateExpression of GeminiDB DynamoDB-Compatible API supports the following syntax:

update-expression ::=
    [ SET action [, action] ... ]
    [ REMOVE action [, action] ...]
    [ ADD action [, action] ... ]
    [ DELETE action [, action] ...]   

set-action ::=
    path = value  

value ::=
    operand
    | operand '+' operand
    | operand '-' operand   

operand ::= 
    path | function  

function ::= 
    if_not_exists (path, value) 
    | list_append (list1, list2)   

remove-action ::=
    path   

add-action ::= 
    path value

delete-action ::= 
    path value
In SET path = operand, operand cannot be set to path.
In SET path = operand1 '+'|'-' operand2, operand1 must be set to path, and operand2 must be an attribute value.
In SET path = if_not_exists (path, value), values of the two path parameters must be the same and must be expression attribute values.
All values can only be placeholders, for example, ':placeholder'.

Compatible APIs

**Table 1** API list
API
CreateTable
UpdateTable
DescribeTable
ListTables
DeleteTable
PutItem
UpdateItem
GetItem
DeleteItem
BatchWriteItem
BatchGetItem
Query
Scan
UpdateTimeToLive
DescribeTimeToLive

**Table 2** CreateTable
API	Parameter		Mandatory	Supported	Remarks
CreateTable	Request parameter	AttributeDefinitions	Yes	Yes	-
		KeySchema	Yes	Yes	-
		TableName	Yes	Yes	Can contain 3 to 48 characters. The regular expression is ([\w-]+).
		BillingMode	No	Yes	-
		GlobalSecondaryIndexes	No	Yes	-
		LocalSecondaryIndexes	No	Yes	-
		ProvisionedThroughput	Yes	Yes	-
		SSESpecification	No	No	-
		StreamSpecification	No	Yes	-
		Tags	No	No	-
	Response parameter	TableDescription	-	Yes	-

**Table 3** UpdateTable
API	Parameter		Mandatory	Supported	Remarks
UpdateTable	Request parameter	AttributeDefinitions	No	Yes	-
		BillingMode	No	Yes	-
		GlobalSecondaryIndexesUpdates	Yes	Yes	-
		ProvisionedThroughput	No	No	-
		ReplicaUpdates	No	No	Default strong consistency
		SSESpecification	No	No	-
		StreamSpecification	No	Yes	-
		TableName	Yes	Yes	-
	Response parameter	TableDescription	-	Yes	-

**Table 4** DescribeTable
API	Parameter		Mandatory	Supported	Remarks
DescribeTable	Request parameter	TableName	Yes	Yes	-
DescribeTable	Response parameter	Table	-	Yes	-

**Table 5** ListTables
API	Parameter		Mandatory	Supported	Remarks
ListTables	Request parameter	ExclusiveStartTableName	No	Yes	-
	Request parameter	Limit	No	Yes	-
	Response parameter	LastEvaluatedTableName	-	Yes	-
	Response parameter	TableNames	-	Yes	-

**Table 6** DeleteTable
API	Parameter		Mandatory	Supported	Remarks
DeleteTable	Request parameter	TableName	Yes	Yes	-
DeleteTable	Response parameter	TableDescription	-	Yes	-

**Table 7** PutItem
API	Parameter		Mandatory	Supported	Remarks
PutItem	Request parameter	Item	Yes	Yes	-
		TableName	Yes	Yes	-
		ConditionalOperator	No	Yes	-
		ConditionExpression	No	Yes	-
		Expected	No	Yes	-
		ExpressionAttributeNames	No	Yes	-
		ExpressionAttributeValues	No	Yes	-
		ReturnConsumedCapacity	No	Yes	-
		ReturnItemCollectionMetrics	No	Yes	-
		ReturnValues	No	Yes	-
	Response parameter	Attributes	-	Yes	-
		ConsumedCapacity	-	Yes	-
		ItemCollectionMetrics	-	No	-

**Table 8** UpdateItem
API	Parameter		Mandatory	Supported	Remarks
UpdateItem	Request parameter	Key	Yes	Yes	-
		TableName	Yes	Yes	-
		AttributeUpdates	No	Yes	-
		ConditionalOperator	No	Yes	-
		ConditionExpression	No	Yes	-
		Expected	No	Yes	-
		ExpressionAttributeNames	No	Yes	-
		ExpressionAttributeValues	No	Yes	-
		ReturnConsumedCapacity	No	Yes	-
		ReturnItemCollectionMetrics	No	No	-
		ReturnValues	No	Yes	-
		UpdateExpression	No	Yes	-
	Response parameter	Attributes	-	Yes	-
		ConsumedCapacity	-	Yes	-
		ItemCollectionMetrics	-	No	-

**Table 9** GetItem
API	Parameter		Mandatory	Supported	Remarks
GetItem	Request parameter	Key	Yes	Yes	-
		TableName	Yes	Yes	-
		AttributesToGet	No	Yes	-
		ConsistentRead	No	No	Default strong consistency
		ExpressionAttributeNames	No	Yes	-
		ProjectionExpression	No	Yes	-
		ReturnConsumedCapacity	No	Yes	-
	Response parameter	ConsumedCapacity	-	Yes	-
	Response parameter	Item	-	Yes	-

**Table 10** DeleteItem
API	Parameter		Mandatory	Supported	Remarks
DeleteItem	Request parameter	Key	Yes	Yes	-
		TableName	Yes	Yes	-
		ConditionalOperator	No	Yes	-
		ConditionExpression	No	Yes	-
		Expected	No	Yes	-
		ExpressionAttributeNames	No	Yes	-
		ExpressionAttributeValues	No	Yes	-
		ReturnConsumedCapacity	No	Yes	-
		ReturnItemCollectionMetrics	No	No	-
		ReturnValues	No	Yes	-
	Response parameter	Attributes	-	Yes	-
		ConsumedCapacity	-	Yes	-
		ItemCollectionMetrics	-	No	-

**Table 11** BatchWriteItem
API	Parameter		Mandatory	Supported	Remarks
BatchWriteItem	Request parameter	RequestItems	Yes	Yes	-
		ReturnConsumedCapacity	No	Yes	-
		ReturnItemCollectionMetrics	No	No	-
	Response parameter	ConsumedCapacity	-	Yes	-
		ItemCollectionMetrics	-	No	-
		UnprocessedItems	-	Yes	-

**Table 12** BatchGetItem
API	Parameter		Mandatory	Supported	Remarks
BatchGetItem	Request parameter	RequestItems	Yes	Yes	None
	Request parameter	ReturnConsumedCapacity	No	Yes	-
	Response parameter	ConsumedCapacity	-	Yes	-
		Responses	-	Yes	-
		UnprocessedKeys	-	Yes	-

**Table 13** Query
API	Parameter		Mandatory	Supported	Remarks
Query	Request parameter	TableName	Yes	Yes	-
		AttributesToGet	No	Yes	-
		ConditionalOperator	No	Yes	-
		ConsistentRead	No	No	Default strong consistency
		ExclusiveStartKey	No	Yes	-
		ExpressionAttributeNames	No	Yes	-
		ExpressionAttributeValues	No	Yes	-
		FilterExpression	No	Yes	-
		IndexName	No	Yes	-
		KeyConditionExpression	No	Yes	-
		KeyConditions	No	No	-
		Limit	No	Yes	-
		ProjectionExpression	No	Yes	-
		QueryFilter	No	Yes	-
		ReturnConsumedCapacity	No	Yes	-
		ScanIndexForward	No	Yes	-
		Select	No	Yes	-
	Response parameter	ConsumedCapacity	-	Yes	-
		Count	-	Yes	-
		Items	-	Yes	-
		LastEvaluatedKey	-	Yes	-
		ScannedCount	-	Yes	-

**Table 14** Scan
API	Parameter		Mandatory	Supported	Remarks
Scan	Request parameter	TableName	Yes	Yes	-
		AttributesToGet	No	Yes	-
		ConditionalOperator	No	Yes	-
		ConsistentRead	No	No	Default strong consistency
		ExclusiveStartKey	No	Yes	-
		ExpressionAttributeNames	No	Yes	-
		ExpressionAttributeValues	No	Yes	-
		FilterExpression	No	Yes	-
		IndexName	No	Yes	-
		Limit	No	Yes	-
		ProjectionExpression	No	Yes	-
		ReturnConsumedCapacity	No	Yes	-
		ScanFilter	No	Yes	-
		Segment	No	Yes	-
		Select	No	Yes	-
		TotalSegments	No	Yes	-
	Response parameter	ConsumedCapacity	No	Yes	-
		Count	-	Yes	-
		Items	-	Yes	-
		LastEvaluatedKey	-	Yes	-
		ScannedCount	-	Yes	-