Tablestore:Read a single row of data

Usage notes

When you read data from a data table, you must provide the complete primary key, including the value of the auto-increment primary key column.

Prerequisites

A client is initialized. For more information, see Initialize a Tablestore client.

Method description

public GetRowResponse getRow(GetRowRequest getRowRequest) throws TableStoreException, ClientException

Sample code

The following sample code reads a single row of data with the primary key value of row1.

public static void getRowExample(SyncClient client) {
    // Construct the primary key.
    PrimaryKeyBuilder primaryKeyBuilder = PrimaryKeyBuilder.createPrimaryKeyBuilder();
    primaryKeyBuilder.addPrimaryKeyColumn("id", PrimaryKeyValue.fromString("row1"));
    PrimaryKey primaryKey = primaryKeyBuilder.build();

    // Construct the row data to read.
    SingleRowQueryCriteria singleRowQueryCriteria = new SingleRowQueryCriteria("test_table", primaryKey);
    singleRowQueryCriteria.setMaxVersions(1);

    // Call the getRow method to read the row data.
    GetRowRequest getRowRequest = new GetRowRequest(singleRowQueryCriteria);
    GetRowResponse getRowResponse = client.getRow(getRowRequest);

    // Return the result.
    System.out.println("RequestId: " + getRowResponse.getRequestId());
    System.out.println("Read CU Cost: " + getRowResponse.getConsumedCapacity().getCapacityUnit().getReadCapacityUnit());
    System.out.println("Write CU Cost: " + getRowResponse.getConsumedCapacity().getCapacityUnit().getWriteCapacityUnit());
    System.out.println("Row Data: \n" + getRowResponse.getRow());
}

• Specify the version range of data to read. Only data within the version range is returned.

  // Set the version range of data to read to one day before the current time.
  singleRowQueryCriteria.setTimeRange(new TimeRange(System.currentTimeMillis() - 86400*1000, System.currentTimeMillis()));

• Specify the attribute columns to read.

  singleRowQueryCriteria.addColumnsToGet("col2");

References

• Use the local transaction feature

• Read data whose primary key values are in the specified range

• Read multiple rows of data at the same time

• Read data by using an iterator

• Use TableStoreReader to read data concurrently