Read with a filter

Read the most recent value in a given column using a filter.

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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. 

StatusOr<std::pair<bool, cbt::Row>> result = table.ReadRow("key-0", filter);
if (!result) throw std::move(result).status();
if (!result->first) {
  std::cout << "Cannot find row 'key-0' in the table: " << table.table_name()
            << "\n";
  return;
}
cbt::Cell const& cell = result->second.cells().front();
std::cout << cell.family_name() << ":" << cell.column_qualifier() << "    @ "
          << cell.timestamp().count() << "us\n"
          << '"' << cell.value() << '"' << "\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. 

// Read from the table.
Console.WriteLine("Read the first row");

int rowIndex = 0;

// Read a specific row. Apply a filter to return latest only cell value accross entire row.
Row rowRead = bigtableClient.ReadRow(
    tableName, rowKey: rowKeyPrefix + rowIndex, filter: filter);
Console.WriteLine(
    $"\tRow key: {rowRead.Key.ToStringUtf8()} " +
    $"  -- Value: {rowRead.Families[0].Columns[0].Cells[0].Value.ToStringUtf8(),-16} " +
    $"  -- Time Stamp: {rowRead.Families[0].Columns[0].Cells[0].TimestampMicros}");

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. 

private void readRowFilter(String tableId, Filter filter) {
  String rowKey =
      Base64.getEncoder().encodeToString("greeting0".getBytes(StandardCharsets.UTF_8));
  Row row = dataClient.readRow(TableId.of(tableId), rowKey, filter);
  printRow(row);
  System.out.println("Row filter completed.");
}

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. 

console.log('Reading a single row by row key');
const [singleRow] = await table.row('greeting0').get({filter});
console.log(`\tRead: ${getRowGreeting(singleRow)}`);

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. 

printf('Getting a single greeting by row key.' . PHP_EOL);
$key = 'greeting0';
// Only retrieve the most recent version of the cell.
$rowFilter = (new RowFilter())->setCellsPerColumnLimitFilter(1);

$column = 'greeting';
$columnFamilyId = 'cf1';

$row = $table->readRow($key, [
    'filter' => $rowFilter
]);
printf('%s' . PHP_EOL, $row[$columnFamilyId][$column][0]['value']);

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("Getting a single greeting by row key.")
key = "greeting0".encode()

row = table.read_row(key, row_filter)
cell = row.cells[column_family_id][column][0]
print(cell.value.decode("utf-8"))

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. 

puts "Reading a single row by row key"
row = table.read_row "greeting0", filter: filter
puts "Row key: #{row.key}, Value: #{row.cells[column_family].first.value}"

What's next

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