Tablestore:Read multiple rows of data at the same time

Usage notes

You can read a maximum of 100 rows of data in a single batch read operation.

Prerequisites

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

Method

public BatchGetRowResponse batchGetRow(BatchGetRowRequest batchGetRowRequest) throws TableStoreException, ClientException

Sample code

The following sample code reads two rows of data with primary key values row1 and row2 from the test_table table.

public static void batchGetRowExample(SyncClient client) {
    // Construct query conditions.
    MultiRowQueryCriteria multiRowQueryCriteria = new MultiRowQueryCriteria("test_table");
    // Add primary key information for the first row.
    PrimaryKeyBuilder primaryKeyBuilder = PrimaryKeyBuilder.createPrimaryKeyBuilder();
    primaryKeyBuilder.addPrimaryKeyColumn("id", PrimaryKeyValue.fromString("row1"));
    multiRowQueryCriteria.addRow(primaryKeyBuilder.build());
    // Add primary key information for the second row.
    primaryKeyBuilder = PrimaryKeyBuilder.createPrimaryKeyBuilder();
    primaryKeyBuilder.addPrimaryKeyColumn("id", PrimaryKeyValue.fromString("row2"));
    multiRowQueryCriteria.addRow(primaryKeyBuilder.build());
    // Specify the version to query.
    multiRowQueryCriteria.setMaxVersions(1);

    // Call the batchGetRow method to perform batch data query.
    BatchGetRowRequest batchGetRowRequest = new BatchGetRowRequest();
    batchGetRowRequest.addMultiRowQueryCriteria(multiRowQueryCriteria);
    BatchGetRowResponse batchGetRowResponse = client.batchGetRow(batchGetRowRequest);

    // Return the result.
    System.out.println("* RequestId: " + batchGetRowResponse.getRequestId());
    System.out.println("* Is all succeeded: " + batchGetRowResponse.isAllSucceed());
    // Print the successfully read rows.
    System.out.println("* Succeeded Rows: ");
    for(BatchGetRowResponse.RowResult rowResult:batchGetRowResponse.getSucceedRows())
        System.out.println(rowResult.getRow());
    // Print the rows that failed to be read.
    if(!batchGetRowResponse.isAllSucceed()) {
        System.out.println("* Failed Rows: ");
        for(BatchGetRowResponse.RowResult rowResult:batchGetRowResponse.getFailedRows())
            System.out.println(rowResult.getTableName() + " | " + batchGetRowRequest.getPrimaryKey(rowResult.getTableName(), rowResult.getIndex()) + " | " + rowResult.getError());
    }
}

You can refer to the following sample code to configure parameters when you read data in a batch.

• Read data from multiple tables. You can read data from multiple tables at a time in a batch read operation. You need to specify a MultiRowQueryCriteria object for each table.

  // Construct query conditions for the second table.
  MultiRowQueryCriteria multiRowQueryCriteria1 = new MultiRowQueryCriteria("orders_small");
  // Add primary key information for the first row.
  primaryKeyBuilder = PrimaryKeyBuilder.createPrimaryKeyBuilder();
  primaryKeyBuilder.addPrimaryKeyColumn("order_id", PrimaryKeyValue.fromString("90fb478c-1360-11f0-a34d-00163e30a2a9"));
  multiRowQueryCriteria1.addRow(primaryKeyBuilder.build());
  // Specify the version to query.
  multiRowQueryCriteria1.setMaxVersions(1);
  // Add MultiRowQueryCriteria to the request.
  batchGetRowRequest.addMultiRowQueryCriteria(multiRowQueryCriteria1);

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

  // Specify the version range to read data from one day ago to the current time.
  multiRowQueryCriteria.setTimeRange(new TimeRange(System.currentTimeMillis() - 86400*1000, System.currentTimeMillis()));

• Specify the attribute columns to read.

  multiRowQueryCriteria.addColumnsToGet("col1");

References

• Use the local transaction feature

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

• Read data by using an iterator

• Use TableStoreReader to read data concurrently