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C++ Client Libraries | Google Cloud

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Advanced Reading and Writing Samples

This example is for advanced reading and writing operations on bigtable data client, that illustrates how to:

Use ReadModifyWrite to append a string to a value.
Use ReadModifyWrite to increment a value.
Use the features to simplify reading big-endian values from Cloud Bigtable.
Use CheckAndMutate to modify a value only if it exists.

Run the example

This example uses the Cloud Bigtable C++ Client Library to communicate with Cloud Bigtable.

To run the example program, follow the instructions for the example on GitHub.

The example uses the following headers:

#include "google/cloud/bigtable/table.h"

Connect to the Cloud Bigtable data client endpoint.

  google::cloud::bigtable::Table table(
      google::cloud::bigtable::MakeDataConnection(),
      google::cloud::bigtable::TableResource(project_id, instance_id,
                                             table_id));

Use ReadModifyWrite to increment a value and append a string to a value.

  namespace cbt = ::google::cloud::bigtable;
  using ::google::cloud::StatusOr;
  [](cbt::Table table, std::string const& row_key) {
    StatusOr<cbt::Row> row = table.ReadModifyWriteRow(
        row_key, cbt::ReadModifyWriteRule::IncrementAmount("fam", "counter", 1),
        cbt::ReadModifyWriteRule::AppendValue("fam", "list", ";element"));

    // As the modify in this example is not idempotent, and this example
    // does not attempt to retry if there is a failure, we simply print
    // such failures, if any, and otherwise ignore them.
    if (!row) {
      std::cout << "Failed to append row: " << row.status().message() << "\n";
      return;
    }
    // Print the contents of the row
    std::cout << row->row_key() << "\n";
    for (auto const& cell : row->cells()) {
      std::cout << "    " << cell.family_name() << ":"
                << cell.column_qualifier() << " = <";
      if (cell.column_qualifier() == "counter") {
        // This example uses "counter" to store 64-bit numbers in big-endian
        // format, extract them as follows:
        std::cout << cell.decode_big_endian_integer<std::int64_t>().value();
      } else {
        std::cout << cell.value();
      }
      std::cout << ">\n";
    }
  }

Use the features to simplify reading big-endian values from Cloud Bigtable.

  namespace cbt = ::google::cloud::bigtable;
  using ::google::cloud::StatusOr;
  [](google::cloud::bigtable::Table table, std::string const& row_key) {
    StatusOr<std::pair<bool, cbt::Row>> tuple = table.ReadRow(
        row_key, cbt::Filter::ColumnName("stats_summary", "os_build"));
    if (!tuple) throw std::move(tuple).status();
    if (!tuple->first) {
      std::cout << "Row " << row_key << " not found\n";
      return;
    }
    PrintRow(tuple->second);
  }

Use CheckAndMutate to modify a cell if it has a value.

  namespace cbt = ::google::cloud::bigtable;
  using ::google::cloud::StatusOr;
  [](cbt::Table table, std::string const& row_key) {
    // Check if the latest value of the flip-flop column is "on".
    cbt::Filter predicate = cbt::Filter::Chain(
        cbt::Filter::ColumnRangeClosed("fam", "flip-flop", "flip-flop"),
        cbt::Filter::Latest(1), cbt::Filter::ValueRegex("on"));
    // If the predicate matches, change the latest value to "off", otherwise,
    // change the latest value to "on".  Modify the "flop-flip" column at the
    // same time.
    StatusOr<cbt::MutationBranch> branch =
        table.CheckAndMutateRow(row_key, std::move(predicate),
                                {cbt::SetCell("fam", "flip-flop", "off"),
                                 cbt::SetCell("fam", "flop-flip", "on")},
                                {cbt::SetCell("fam", "flip-flop", "on"),
                                 cbt::SetCell("fam", "flop-flip", "off")});

    if (!branch) throw std::move(branch).status();
    if (*branch == cbt::MutationBranch::kPredicateMatched) {
      std::cout << "The predicate was matched\n";
    } else {
      std::cout << "The predicate was not matched\n";
    }
  }

Use CheckAndMutate to modify a cell if another cell exists.

  namespace cbt = ::google::cloud::bigtable;
  using ::google::cloud::StatusOr;
  [](cbt::Table table, std::string const& row_key) {
    // Check if the latest value of the "test-column" column is present,
    // regardless of its value.
    cbt::Filter predicate = cbt::Filter::Chain(
        cbt::Filter::ColumnRangeClosed("fam", "test-column", "test-column"),
        cbt::Filter::Latest(1));
    // If the predicate matches, do nothing, otherwise set the
    // "had-test-column" to "false":
    StatusOr<cbt::MutationBranch> branch = table.CheckAndMutateRow(
        row_key, std::move(predicate), {},
        {cbt::SetCell("fam", "had-test-column", "false")});

    if (!branch) throw std::move(branch).status();
    if (*branch == cbt::MutationBranch::kPredicateMatched) {
      std::cout << "The predicate was matched\n";
    } else {
      std::cout << "The predicate was not matched\n";
    }
  }

Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025-08-14 UTC.

[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Hard to understand","hardToUnderstand","thumb-down"],["Incorrect information or sample code","incorrectInformationOrSampleCode","thumb-down"],["Missing the information/samples I need","missingTheInformationSamplesINeed","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-14 UTC."],[[["This page provides access to various versions of the Cloud Bigtable C++ Client Library documentation, ranging from version 2.11.0 to the latest release candidate 2.37.0-rc."],["The content showcases examples of advanced reading and writing operations using the Cloud Bigtable data client, including appending strings and incrementing values using `ReadModifyWrite`."],["It demonstrates how to read big-endian values directly from Cloud Bigtable data using the provided features that simplify the process."],["The examples also illustrate the usage of `CheckAndMutate` to conditionally modify cell values based on the presence or content of other cells."],["The example programs in this content use the Cloud Bigtable C++ Client Library and a link to the library instructions is provided to run them."]]],[]]

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