使用过期项目和生存时间（TTL）

查询对表达式进行了筛选，以使用Amazon SDK for Java 2.x 在 DynamoDB 表中收集 TTL 项目。

import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.QueryRequest;
import software.amazon.awssdk.services.dynamodb.model.QueryResponse;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;

import java.util.Map;
import java.util.Optional;

        final QueryRequest request = QueryRequest.builder()
            .tableName(tableName)
            .keyConditionExpression(KEY_CONDITION_EXPRESSION)
            .filterExpression(FILTER_EXPRESSION)
            .expressionAttributeNames(expressionAttributeNames)
            .expressionAttributeValues(expressionAttributeValues)
            .build();

        try (DynamoDbClient ddb = dynamoDbClient != null
            ? dynamoDbClient
            : DynamoDbClient.builder().region(region).build()) {
            final QueryResponse response = ddb.query(request);
            System.out.println("Query successful. Found " + response.count() + " items that have not expired yet.");

            // Print each item
            response.items().forEach(item -> {
                System.out.println("Item: " + item);
            });

            return 0;
        } catch (ResourceNotFoundException e) {
            System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
            throw e;
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            throw e;
        }

查询对表达式进行了筛选，以使用适用于 JavaScript 的 Amazon SDK 在 DynamoDB 表中收集 TTL 项目。

import { DynamoDBClient, QueryCommand } from "@aws-sdk/client-dynamodb";
import { marshall, unmarshall } from "@aws-sdk/util-dynamodb";

export const queryFiltered = async (tableName, primaryKey, region = 'us-east-1') => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const currentTime = Math.floor(Date.now() / 1000);

    const params = {
        TableName: tableName,
        KeyConditionExpression: "#pk = :pk",
        FilterExpression: "#ea > :ea",
        ExpressionAttributeNames: {
            "#pk": "primaryKey",
            "#ea": "expireAt"
        },
        ExpressionAttributeValues: marshall({
            ":pk": primaryKey,
            ":ea": currentTime
        })
    };

    try {
        const { Items } = await client.send(new QueryCommand(params));
        Items.forEach(item => {
            console.log(unmarshall(item))
        });
        return Items;
    } catch (err) {
        console.error(`Error querying items: ${err}`);
        throw err;
    }
}

// Example usage (commented out for testing)
// queryFiltered('your-table-name', 'your-partition-key-value');

查询对表达式进行了筛选，以使用适用于 Python (Boto3) 的 Amazon SDK 在 DynamoDB 表中收集 TTL 项目。

from datetime import datetime

import boto3


def query_dynamodb_items(table_name, partition_key):
    """

    :param table_name: Name of the DynamoDB table
    :param partition_key:
    :return:
    """
    try:
        # Initialize a DynamoDB resource
        dynamodb = boto3.resource("dynamodb", region_name="us-east-1")

        # Specify your table
        table = dynamodb.Table(table_name)

        # Get the current time in epoch format
        current_time = int(datetime.now().timestamp())

        # Perform the query operation with a filter expression to exclude expired items
        # response = table.query(
        #    KeyConditionExpression=boto3.dynamodb.conditions.Key('partitionKey').eq(partition_key),
        #    FilterExpression=boto3.dynamodb.conditions.Attr('expireAt').gt(current_time)
        # )
        response = table.query(
            KeyConditionExpression=dynamodb.conditions.Key("partitionKey").eq(partition_key),
            FilterExpression=dynamodb.conditions.Attr("expireAt").gt(current_time),
        )

        # Print the items that are not expired
        for item in response["Items"]:
            print(item)

    except Exception as e:
        print(f"Error querying items: {e}")


# Call the function with your values
query_dynamodb_items("Music", "your-partition-key-value")

使用条件更新表中现有 DynamoDB 项目的 TTL。

package com.amazon.samplelib.ttl;

import com.amazon.samplelib.CodeSampleUtils;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.ConditionalCheckFailedException;
import software.amazon.awssdk.services.dynamodb.model.DynamoDbException;
import software.amazon.awssdk.services.dynamodb.model.ResourceNotFoundException;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemRequest;
import software.amazon.awssdk.services.dynamodb.model.UpdateItemResponse;

import java.util.Map;
import java.util.Optional;

/**
 * Updates an item in a DynamoDB table with TTL attributes using a conditional expression.
 * This class demonstrates how to conditionally update TTL expiration timestamps.
 */
public class UpdateTTLConditional {

    private static final String USAGE =
        """
            Usage:
                <tableName> <primaryKey> <sortKey> <region>
            Where:
                tableName - The Amazon DynamoDB table being queried.
                primaryKey - The name of the primary key. Also known as the hash or partition key.
                sortKey - The name of the sort key. Also known as the range attribute.
                region (optional) - The AWS region that the Amazon DynamoDB table is located in. (Default: us-east-1)
            """;
    private static final int DAYS_TO_EXPIRE = 90;
    private static final int SECONDS_PER_DAY = 24 * 60 * 60;
    private static final String PRIMARY_KEY_ATTR = "primaryKey";
    private static final String SORT_KEY_ATTR = "sortKey";
    private static final String UPDATED_AT_ATTR = "updatedAt";
    private static final String EXPIRE_AT_ATTR = "expireAt";
    private static final String UPDATE_EXPRESSION = "SET " + UPDATED_AT_ATTR + "=:c, " + EXPIRE_AT_ATTR + "=:e";
    private static final String CONDITION_EXPRESSION = "attribute_exists(" + PRIMARY_KEY_ATTR + ")";
    private static final String SUCCESS_MESSAGE = "%s UpdateItem operation with TTL successful.";
    private static final String CONDITION_FAILED_MESSAGE = "Condition check failed. Item does not exist.";
    private static final String TABLE_NOT_FOUND_ERROR = "Error: The Amazon DynamoDB table \"%s\" can't be found.";

    private final DynamoDbClient dynamoDbClient;

    /**
     * Constructs an UpdateTTLConditional with a default DynamoDB client.
     */
    public UpdateTTLConditional() {
        this.dynamoDbClient = null;
    }

    /**
     * Constructs an UpdateTTLConditional with the specified DynamoDB client.
     *
     * @param dynamoDbClient The DynamoDB client to use
     */
    public UpdateTTLConditional(final DynamoDbClient dynamoDbClient) {
        this.dynamoDbClient = dynamoDbClient;
    }

    /**
     * Main method to demonstrate conditionally updating an item with TTL.
     *
     * @param args Command line arguments
     */
    public static void main(final String[] args) {
        try {
            int result = new UpdateTTLConditional().processArgs(args);
            System.exit(result);
        } catch (Exception e) {
            System.err.println(e.getMessage());
            System.exit(1);
        }
    }

    /**
     * Process command line arguments and conditionally update an item with TTL.
     *
     * @param args Command line arguments
     * @return 0 if successful, non-zero otherwise
     * @throws ResourceNotFoundException If the table doesn't exist
     * @throws DynamoDbException If an error occurs during the operation
     * @throws IllegalArgumentException If arguments are invalid
     */
    public int processArgs(final String[] args) {
        // Argument validation (remove or replace this line when reusing this code)
        CodeSampleUtils.validateArgs(args, new int[] {3, 4}, USAGE);

        final String tableName = args[0];
        final String primaryKey = args[1];
        final String sortKey = args[2];
        final Region region = Optional.ofNullable(args.length > 3 ? args[3] : null)
            .map(Region::of)
            .orElse(Region.US_EAST_1);

        // Get current time in epoch second format
        final long currentTime = System.currentTimeMillis() / 1000;

        // Calculate expiration time 90 days from now in epoch second format
        final long expireDate = currentTime + (DAYS_TO_EXPIRE * SECONDS_PER_DAY);

        // Create the key map for the item to update
        final Map<String, AttributeValue> keyMap = Map.of(
            PRIMARY_KEY_ATTR, AttributeValue.builder().s(primaryKey).build(),
            SORT_KEY_ATTR, AttributeValue.builder().s(sortKey).build());

        // Create the expression attribute values
        final Map<String, AttributeValue> expressionAttributeValues = Map.of(
            ":c", AttributeValue.builder().n(String.valueOf(currentTime)).build(),
            ":e", AttributeValue.builder().n(String.valueOf(expireDate)).build());

        final UpdateItemRequest request = UpdateItemRequest.builder()
            .tableName(tableName)
            .key(keyMap)
            .updateExpression(UPDATE_EXPRESSION)
            .conditionExpression(CONDITION_EXPRESSION)
            .expressionAttributeValues(expressionAttributeValues)
            .build();

        try (DynamoDbClient ddb = dynamoDbClient != null
            ? dynamoDbClient
            : DynamoDbClient.builder().region(region).build()) {
            final UpdateItemResponse response = ddb.updateItem(request);
            System.out.println(String.format(SUCCESS_MESSAGE, tableName));
            return 0;
        } catch (ConditionalCheckFailedException e) {
            System.err.println(CONDITION_FAILED_MESSAGE);
            throw e;
        } catch (ResourceNotFoundException e) {
            System.err.format(TABLE_NOT_FOUND_ERROR, tableName);
            throw e;
        } catch (DynamoDbException e) {
            System.err.println(e.getMessage());
            throw e;
        }
    }
}

使用条件更新表中现有 DynamoDB 项目的 TTL。

import { DynamoDBClient, UpdateItemCommand } from "@aws-sdk/client-dynamodb";
import { marshall, unmarshall } from "@aws-sdk/util-dynamodb";

export const updateItemConditional = async (tableName, partitionKey, sortKey, region = 'us-east-1', newAttribute = 'default-value') => {
    const client = new DynamoDBClient({
        region: region,
        endpoint: `https://dynamodb.${region}.amazonaws.com`
    });

    const currentTime = Math.floor(Date.now() / 1000);

    const params = {
        TableName: tableName,
        Key: marshall({
            artist: partitionKey,
            album: sortKey
        }),
        UpdateExpression: "SET newAttribute = :newAttribute",
        ConditionExpression: "expireAt > :expiration",
        ExpressionAttributeValues: marshall({
            ':newAttribute': newAttribute,
            ':expiration': currentTime
        }),
        ReturnValues: "ALL_NEW"
    };

    try {
        const response = await client.send(new UpdateItemCommand(params));
        const responseData = unmarshall(response.Attributes);
        console.log("Item updated successfully: ", responseData);
        return responseData;
    } catch (error) {
        if (error.name === "ConditionalCheckFailedException") {
            console.log("Condition check failed: Item's 'expireAt' is expired.");
        } else {
            console.error("Error updating item: ", error);
        }
        throw error;
    }
};

// Example usage (commented out for testing)
// updateItemConditional('your-table-name', 'your-partition-key-value', 'your-sort-key-value');

使用条件更新表中现有 DynamoDB 项目的 TTL。

from datetime import datetime, timedelta

import boto3
from botocore.exceptions import ClientError


def update_dynamodb_item_ttl(table_name, region, primary_key, sort_key, ttl_attribute):
    """
    Updates an existing record in a DynamoDB table with a new or updated TTL attribute.

    :param table_name: Name of the DynamoDB table
    :param region: AWS Region of the table - example `us-east-1`
    :param primary_key: one attribute known as the partition key.
    :param sort_key: Also known as a range attribute.
    :param ttl_attribute: name of the TTL attribute in the target DynamoDB table
    :return:
    """
    try:
        dynamodb = boto3.resource("dynamodb", region_name=region)
        table = dynamodb.Table(table_name)

        # Generate updated TTL in epoch second format
        updated_expiration_time = int((datetime.now() + timedelta(days=90)).timestamp())

        # Define the update expression for adding/updating a new attribute
        update_expression = "SET newAttribute = :val1"

        # Define the condition expression for checking if 'expireAt' is not expired
        condition_expression = "expireAt > :val2"

        # Define the expression attribute values
        expression_attribute_values = {":val1": ttl_attribute, ":val2": updated_expiration_time}

        response = table.update_item(
            Key={"primaryKey": primary_key, "sortKey": sort_key},
            UpdateExpression=update_expression,
            ConditionExpression=condition_expression,
            ExpressionAttributeValues=expression_attribute_values,
        )

        print("Item updated successfully.")
        return response["ResponseMetadata"]["HTTPStatusCode"]  # Ideally a 200 OK
    except ClientError as e:
        if e.response["Error"]["Code"] == "ConditionalCheckFailedException":
            print("Condition check failed: Item's 'expireAt' is expired.")
        else:
            print(f"Error updating item: {e}")
    except Exception as e:
        print(f"Error updating item: {e}")


# replace with your values
update_dynamodb_item_ttl(
    "your-table-name",
    "us-east-1",
    "your-partition-key-value",
    "your-sort-key-value",
    "your-ttl-attribute-value",
)