Maximum number of versions

Create a column family with a garbage-collection policy that states the number of versions to keep.

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For detailed documentation that includes this code sample, see the following:

Code sample

C++

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

namespace cbt = ::google::cloud::bigtable;
namespace cbta = ::google::cloud::bigtable_admin;
using ::google::bigtable::admin::v2::ModifyColumnFamiliesRequest;
using ::google::cloud::StatusOr;
[](cbta::BigtableTableAdminClient admin, std::string const& project_id,
   std::string const& instance_id, std::string const& table_id,
   std::string const& family_name) {
  std::string table_name = cbt::TableName(project_id, instance_id, table_id);

  ModifyColumnFamiliesRequest::Modification mod;
  mod.set_id(family_name);
  mod.mutable_create()->mutable_gc_rule()->set_max_num_versions(2);

  StatusOr<google::bigtable::admin::v2::Table> schema =
      admin.ModifyColumnFamilies(table_name, {std::move(mod)});

  if (!schema) throw std::move(schema).status();
  std::cout << "Schema modified to: " << schema->DebugString() << "\n";
}

C#

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// Create a column family with GC policy : most recent N versions
// where 1 = most recent version
// Initialize request argument(s).
// Define the GC policy to retain only the most recent 2 versions
GcRule maxVersionsRule = new GcRule { MaxNumVersions = 2 };

// Column family to create
ColumnFamily columnFamily = new ColumnFamily { GcRule = maxVersionsRule };

TableName tableName = new TableName(projectId, instanceId, tableId);

// Modification to create column family
ModifyColumnFamiliesRequest.Types.Modification modification = new ModifyColumnFamiliesRequest.Types.Modification
{
    Create = columnFamily,
    Id = "cf2"
};

ModifyColumnFamiliesRequest request = new ModifyColumnFamiliesRequest
{
    TableName = tableName,
    Modifications = { modification }
};
try
{
    // Make the request
    Table response = bigtableTableAdminClient.ModifyColumnFamilies(request);
    Console.WriteLine("Created column family");
}
catch (Exception ex)
{
    Console.WriteLine($"Error creating column family {ex.Message}");
}

Go

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import (
	"context"
	"fmt"
	"io"

	"cloud.google.com/go/bigtable"
)

func createFamilyGCMaxVersions(w io.Writer, projectID, instanceID string, tableName string) error {
	// projectID := "my-project-id"
	// instanceID := "my-instance-id"
	// tableName := "my-table-name"

	ctx := context.Background()

	adminClient, err := bigtable.NewAdminClient(ctx, projectID, instanceID)
	if err != nil {
		return fmt.Errorf("bigtable.NewAdminClient: %w", err)
	}
	defer adminClient.Close()

	columnFamilyName := "cf2"
	if err := adminClient.CreateColumnFamily(ctx, tableName, columnFamilyName); err != nil {
		return fmt.Errorf("CreateColumnFamily(%s): %w", columnFamilyName, err)
	}

	// Set a garbage collection policy of 2 versions.
	policy := bigtable.MaxVersionsPolicy(2)
	if err := adminClient.SetGCPolicy(ctx, tableName, columnFamilyName, policy); err != nil {
		return fmt.Errorf("SetGCPolicy(%s): %w", policy, err)
	}

	fmt.Fprintf(w, "created column family %s with policy: %v\n", columnFamilyName, policy)
	return nil
}

Java

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// Creates a column family with GC policy : most recent N versions
// where 1 = most recent version

// Defines the GC policy to retain only the most recent 2 versions.
VersionRule versionRule = GCRULES.maxVersions(2);

// Creates column family with given GC rule.
try {
  // ModifyColumnFamiliesRequest can be used both for adding and modifying families, here it is
  // being used to add a family
  ModifyColumnFamiliesRequest columnFamiliesRequest =
      ModifyColumnFamiliesRequest.of(tableId).addFamily(COLUMN_FAMILY_2, versionRule);
  adminClient.modifyFamilies(columnFamiliesRequest);
  System.out.println("Created column family: " + COLUMN_FAMILY_2);
} catch (AlreadyExistsException e) {
  System.err.println(
      "Failed to create column family with rule, already exists: " + e.getMessage());
}

Node.js

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// Create a column family with GC policy : most recent N versions
// where 1 = most recent version

// Define the GC policy to retain only the most recent 2 versions
const maxVersionsRule = {
  rule: {
    versions: 2,
  },
};

// Create a column family with given GC rule
[family] = await table.createFamily('cf2', maxVersionsRule);
console.log(`Created column family ${family.id}`);

PHP

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

use Google\Cloud\Bigtable\Admin\V2\Client\BigtableTableAdminClient;
use Google\Cloud\Bigtable\Admin\V2\ColumnFamily;
use Google\Cloud\Bigtable\Admin\V2\GcRule;
use Google\Cloud\Bigtable\Admin\V2\ModifyColumnFamiliesRequest;
use Google\Cloud\Bigtable\Admin\V2\ModifyColumnFamiliesRequest\Modification;

/**
 * Create a new column family with a max versions GC rule
 *
 * @param string $projectId The Google Cloud project ID
 * @param string $instanceId The ID of the Bigtable instance where the table resides
 * @param string $tableId The ID of the table in which the rule needs to be created
 */
function create_family_gc_max_versions(
    string $projectId,
    string $instanceId,
    string $tableId
): void {
    $tableAdminClient = new BigtableTableAdminClient();

    $tableName = $tableAdminClient->tableName($projectId, $instanceId, $tableId);

    print('Creating column family cf2 with max versions GC rule...' . PHP_EOL);
    $columnFamily2 = new ColumnFamily();
    $maxVersionRule = (new GcRule())->setMaxNumVersions(2);
    $columnFamily2->setGCRule($maxVersionRule);

    $columnModification = new Modification();
    $columnModification->setId('cf2');
    $columnModification->setCreate($columnFamily2);
    $modifyColumnFamiliesRequest = (new ModifyColumnFamiliesRequest())
        ->setName($tableName)
        ->setModifications([$columnModification]);
    $tableAdminClient->modifyColumnFamilies($modifyColumnFamiliesRequest);

    print('Created column family cf2 with Max Versions GC Rule.' . PHP_EOL);
}

Python

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

    print("Creating column family cf2 with max versions GC rule...")
    # Create a column family with GC policy : most recent N versions
    # where 1 = most recent version

    # Define the GC policy to retain only the most recent 2 versions
    max_versions_rule = column_family.MaxVersionsGCRule(2)

    column_family2 = table.column_family("cf2", max_versions_rule)
    column_family2.create()
    print("Created column family cf2 with Max Versions GC Rule.")

Ruby

To learn how to install and use the client library for Bigtable, see Bigtable client libraries.

To authenticate to Bigtable, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

# Create a column family with GC policy : most recent N versions
# where 1 = most recent version
max_versions_rule = Google::Cloud::Bigtable::GcRule.max_versions 2
column_families = table.column_families do |cfs|
  cfs.add "cf2", gc_rule: max_versions_rule
end
family = column_families["cf2"]

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