Tablestore:Read data in a range

Prerequisites

Initialize a Tablestore client

Method

getRange: function getRange(params, callback)

Examples

The following sample code shows how to read data from the test_table table where the primary key value is greater than row1.

var params = {
    tableName: 'test_table',
    // Set the start primary key for the query.
    inclusiveStartPrimaryKey: [{ 'id': 'row1' }],
    // Set the end primary key for the query. The end primary key is not included in the result.
    exclusiveEndPrimaryKey: [{ 'id': TableStore.INF_MAX }]
};

// Call the getRange method to query data.
client.getRange(params, function (err, data) {
    if (err) {
        console.log('Get range failed with error: ', err);
        return;
    }

    console.log('* RequestId: ', data.RequestId);
    console.log('* Read CU Cost: ', data.consumed.capacityUnit.read);
    console.log('* Write CU Cost: ', data.consumed.capacityUnit.write);
    console.log('* Rows Data: ');
    data.rows.forEach(function (row) {
         console.log(row);
    });
});

A single range scan can return a maximum of 5,000 rows or 4 MB of data. If this limit is exceeded, the operation returns the start primary key for the next read. You can use the following code to perform an iterative query.

async function getRangeSample() {
    try {
        while (true) {
            // Call the getRange method to query data.
            const data = await client.getRange(params);

            // Process the returned result.
            console.log('* RequestId: ', data.RequestId);
            console.log('* Read CU Cost: ', data.consumed.capacityUnit.read);
            console.log('* Write CU Cost: ', data.consumed.capacityUnit.write);
            console.log('* Rows Data: ');
            data.rows.forEach(function (row) {
                console.log(row);
            });

            // Set the start primary key for the next read.
            if (data.nextStartPrimaryKey) {
                params.inclusiveStartPrimaryKey = data.nextStartPrimaryKey.map(item => {
                    return {
                        [item.name]: item.value
                    };
                });
            } else {
                break;
            }
        }
    } catch (err) {
        console.log('Range get failed with error: ', err);
    }
}

getRangeSample();

Also configure the following settings when you query data.

• Set the data read direction.

  var params = {
      tableName: 'test_table',
      // Set the start primary key for the query. When you read data in reverse order, the start primary key must be greater than the end primary key.
      inclusiveStartPrimaryKey: [{ 'id': TableStore.INF_MAX }],
      // Set the end primary key for the query. The end primary key is not included in the result.
      exclusiveEndPrimaryKey: [{ 'id': 'row1' }],
      // Set the read direction to reverse.
      direction: TableStore.Direction.BACKWARD
  };

• Set the version range of the data to read. The operation returns only data within the specified version range.

  // Set the version range for the query to the last 24 hours.
  params.timeRange = {
      startTime: (Date.now() - 86400 * 1000).toString(),
      endTime: Date.now().toString()
  }

• Specify the attribute columns to read.

  params.columnsToGet = ['col2']

• Set the maximum number of rows to return in a single request.

  params.limit = 10

References

Batch Read Data