(TypeScript+AWS SDK v3)DynamoDBテーブルから全レコードを削除する関数 (Delete all records from a DynamoDB table)

dynamodb-helper.ts

import {
  DescribeTableCommand,
  DynamoDBClient,
  ListTablesCommand,
  ScanCommand,
  BatchWriteItemCommand,
  ScanCommandOutput,
  AttributeValue,
} from '@aws-sdk/client-dynamodb';

/**
 * 指定したDynamoDBのテーブル名のテーブルから全てのItemを取得するジェネレータ
 * @param tableName DynamoDBのテーブル名
 */
const createItemGenerator = async function* (dynamoDBClient: DynamoDBClient, tableName: string) {
  let LastEvaluatedKey;

  while (true) {
    const scanRes: ScanCommandOutput = await dynamoDBClient.send(
      new ScanCommand({ TableName: tableName, ExclusiveStartKey: LastEvaluatedKey }),
    );
    for (const item of scanRes.Items ?? []) {
      yield item;
    }
    if (!scanRes.LastEvaluatedKey) {
      break;
    }
    LastEvaluatedKey = scanRes.LastEvaluatedKey;
  }
};

/**
 * イテレータから決まった要素数だけ切り出すジェネレータを生成します
 * @param iterable イテレータ
 * @param batchSize 分割サイズ
 */
const batch = async function* batch<T>(iterable: AsyncIterableIterator<T>, batchSize: number) {
  let items: T[] = [];
  for await (const item of iterable) {
    items.push(item);
    if (items.length >= batchSize) {
      yield items;
      items = [];
    }
  }
  if (items.length !== 0) {
    yield items;
  }
};

/**
 * テーブルの一覧を取得します。
 * メモ化されています。
 */
const getTableMetaData = (function () {
  let memorize: {
    [tableName: string]: {
      /** レコードから一意のキーの値だけを持つレコードに変換する（削除で使用） */
      selectPrimaryKey: (record: Record<string, AttributeValue>) => Record<string, AttributeValue>;
    };
  };
  return async (dynamoDBClient: DynamoDBClient) => {
    // テーブルの一覧取得
    if (!memorize) {
      memorize = {};
      const res = await dynamoDBClient.send(new ListTablesCommand({ Limit: 100 }));
      for (const tableName of res.TableNames ?? []) {
        const describe = await dynamoDBClient.send(new DescribeTableCommand({ TableName: tableName }));

        const keySchema = describe.Table?.KeySchema;
        const pk = keySchema?.find((key) => key.KeyType === 'HASH'); // Partition Key
        const sk = keySchema?.find((key) => key.KeyType === 'RANGE'); // Sort Key

        if (!pk) {
          throw new Error(`Undefined partitionKey table. tableName=${tableName}, keySchema=${keySchema}`);
        }
        memorize[tableName] = {
          selectPrimaryKey(record) {
            return {
              [pk.AttributeName as string]: record[pk.AttributeName as string],
              ...(sk ? { [sk.AttributeName as string]: record[sk.AttributeName as string] } : {}),
            };
          },
        };
      }
    }
    return memorize;
  };
})();

/**
 * 指定したDynamoDBテーブルのレコードをすべて削除します。
 *
 * @param tableName テーブル名
 */
export const clearTable = async (dynamoDBClient: DynamoDBClient, tableName: string) => {
  const tableInfo = await getTableMetaData(dynamoDBClient);

  const { selectPrimaryKey: selectKey } = tableInfo[tableName];

  for await (const chunk of batch(createItemGenerator(dynamoDBClient, tableName), 25)) {
    await dynamoDBClient.send(
      new BatchWriteItemCommand({
        RequestItems: {
          [tableName]: chunk.map((m) => {
            return {
              DeleteRequest: {
                Key: selectKey(m),
              },
            };
          }),
        },
      }),
    );
  }
};

/**
 * すべてのDynamoDBテーブルのレコードを削除します。
 */
export const clearAllTables = async (dynamoDBClient: DynamoDBClient) => {
  const tableInfo = await getTableMetaData(dynamoDBClient);
  await Promise.all(Object.keys(tableInfo).map((t) => clearTable(dynamoDBClient, t)));
};

LICENSE

Copyright (c) 2023 fukasawah

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