步驟 6：檢視文件的修訂歷程記錄

重要

支援結束通知：現有客戶將能夠使用 Amazon，QLDB直到 2025 年 7 月 31 日終止支援為止。有關更多詳細信息，請參閱將 Amazon QLDB 分類帳遷移到 Amazon Aurora 郵政. SQL

在上一個步驟中修改車輛的註冊資料後，您可以查詢其所有註冊車主的歷史記錄以及任何其他更新的欄位。在此步驟中，您會查詢vehicle-registration分類帳VehicleRegistration表格中文件的修訂歷史記錄。

若要檢視修訂歷史記錄

檢閱下列程式 (QueryHistory.java)。

2.x


/*
 * Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: MIT-0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package software.amazon.qldb.tutorial;

import java.io.IOException;
import java.time.Instant;
import java.time.temporal.ChronoUnit;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.amazon.ion.IonValue;

import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.SampleData;
import software.amazon.qldb.tutorial.model.VehicleRegistration;

/**
 * Query a table's history for a particular set of documents.
 *
 * This code expects that you have AWS credentials setup per:
 * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
 */
public final class QueryHistory {
    public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
    private static final int THREE_MONTHS = 90;

    private QueryHistory() { }

    /**
     * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              VIN to find previous primary owners for.
     * @param query
     *              The query to find previous primary owners.
     * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
     */
    public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
        try {
            final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);

            log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
            final Result result = txn.execute(query, Constants.MAPPER.writeValueAsIonValue(docId));
            ScanTable.printDocuments(result);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
        final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                           + "FROM history(VehicleRegistration, `%s`) "
                                           + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
        ConnectToLedger.getDriver().execute(txn -> {
            final String vin = SampleData.VEHICLES.get(0).getVin();
            previousPrimaryOwners(txn, vin, query);
        });
        log.info("Successfully queried history.");
    }
}

1.x


/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: MIT-0
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package software.amazon.qldb.tutorial;

import com.amazon.ion.IonValue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import software.amazon.qldb.QldbSession;
import software.amazon.qldb.Result;
import software.amazon.qldb.TransactionExecutor;
import software.amazon.qldb.tutorial.model.SampleData;
import software.amazon.qldb.tutorial.model.VehicleRegistration;

import java.io.IOException;
import java.time.Instant;
import java.time.temporal.ChronoUnit;
import java.util.Collections;
import java.util.List;

/**
 * Query a table's history for a particular set of documents.
 *
 * This code expects that you have AWS credentials setup per:
 * http://docs.aws.amazon.com/java-sdk/latest/developer-guide/setup-credentials.html
 */
public final class QueryHistory {
    public static final Logger log = LoggerFactory.getLogger(QueryHistory.class);
    private static final int THREE_MONTHS = 90;

    private QueryHistory() { }

    /**
     * In this example, query the 'VehicleRegistration' history table to find all previous primary owners for a VIN.
     *
     * @param txn
     *              The {@link TransactionExecutor} for lambda execute.
     * @param vin
     *              VIN to find previous primary owners for.
     * @param query
     *              The query to find previous primary owners.
     * @throws IllegalStateException if failed to convert document ID to an {@link IonValue}.
     */
    public static void previousPrimaryOwners(final TransactionExecutor txn, final String vin, final String query) {
        try {
            final String docId = VehicleRegistration.getDocumentIdByVin(txn, vin);
            final List<IonValue> parameters = Collections.singletonList(Constants.MAPPER.writeValueAsIonValue(docId));
            log.info("Querying the 'VehicleRegistration' table's history using VIN: {}...", vin);
            final Result result = txn.execute(query, parameters);
            ScanTable.printDocuments(result);
        } catch (IOException ioe) {
            throw new IllegalStateException(ioe);
        }
    }

    public static void main(final String... args) {
        final String threeMonthsAgo = Instant.now().minus(THREE_MONTHS, ChronoUnit.DAYS).toString();
        final String query = String.format("SELECT data.Owners.PrimaryOwner, metadata.version "
                                           + "FROM history(VehicleRegistration, `%s`) "
                                           + "AS h WHERE h.metadata.id = ?", threeMonthsAgo);
        ConnectToLedger.getDriver().execute(txn -> {
            final String vin = SampleData.VEHICLES.get(0).getVin();
            previousPrimaryOwners(txn, vin, query);
        }, (retryAttempt) -> log.info("Retrying due to OCC conflict..."));
        log.info("Successfully queried history.");
    }
}

注意

您可以使用下列語法查詢內建的文件，以檢視文件歷史功能的修訂歷程記錄。


SELECT * FROM history( table_name [, `start-time` [, `end-time` ] ] ) AS h
[ WHERE h.metadata.id = 'id' ]

開始時間和結束時間都是可選的。它們是 Amazon 離子字面值，可以用反引號（）`...`表示。如需進一步了解，請參閱在 Amazon 中使用 PartiQL 查詢離子 QLDB。
最佳作法是使用日期範圍 (開始時間和結束時間) 和文件 ID (metadata.id) 來限定歷史查詢。QLDB處理交易中受到交易逾時限制的SELECT查詢。

QLDB歷史記錄是以文件 ID 編製索引，而且您目前無法建立其他歷史記錄索引。包含開始時間和結束時間的歷史查詢可獲得日期範圍限定的好處。

編譯並執行QueryHistory.java程式，以查詢VehicleRegistration文件的修訂歷程記錄VIN1N4AL11D75C109151。

若要以密碼編譯方式驗證vehicle-registration分類帳中的文件版次，請繼續執行步驟 7：驗證分類帳中的文件。

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文件慣用形式

步驟 5：修改文件

步驟 7：驗證文件