Use Tablestore SDK for Java to specify an auto-increment primary key column - Tablestore

This topic describes how to configure an auto-increment primary key column for a data table by using Tablestore SDK for Java. This topic also explains how to write data to the auto-increment primary key column and retrieve the values of the auto-increment primary key column.

Usage notes

The auto-incremental primary key column feature is supported by Tablestore SDK for Java V4.2.0 and later.
The values generated for an auto-increment primary key column are unique and increase monotonically within a partition. However, the values may not be consecutive.

Prerequisites

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

Configure an auto-increment primary key column

When you create a data table, you can specify a primary key column that is not the partition key as an auto-increment primary key column. You cannot specify an auto-increment primary key column for an existing data table.

Note

A primary key column only of the Integer type can be specified as an auto-increment primary key column. A data table can have at most one auto-increment primary key column. The values generated for an auto-increment primary key column are 64-bit signed long integers.

Sample code

The following sample code provides an example on how to create a data table named test_table. In this example, the data table contains a partition key named id and an auto-increment primary key column named incr.

public static void createTableTest(SyncClient client) {
    TableMeta tableMeta = new TableMeta("test_table");
    tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema("id", PrimaryKeyType.STRING));
    tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema("incr", PrimaryKeyType.INTEGER, PrimaryKeyOption.AUTO_INCREMENT));

    TableOptions tableOptions = new TableOptions();
    tableOptions.setMaxVersions(1);
    tableOptions.setTimeToLive(-1);

    CreateTableRequest createTableRequest = new CreateTableRequest(tableMeta, tableOptions);
    client.createTable(createTableRequest);
}

Write data

When you write data to a data table that contains an auto-increment primary key column, you only need to set the value of the auto-increment primary key column to a placeholder. If you want to obtain the generated value of the auto-increment primary key column for subsequent query and update operations, set the return type of rowPutChange to RT_PK.

Sample code

The following sample code provides an example on how to write a row of data to the test_table table, and obtain and print the primary key information of the row:

public static void putRowTest(SyncClient client) {
    // Construct the primary key.
    PrimaryKeyBuilder primaryKeyBuilder = PrimaryKeyBuilder.createPrimaryKeyBuilder();
    primaryKeyBuilder.addPrimaryKeyColumn("id", PrimaryKeyValue.fromString("row1"));
    // Set the value of the auto-increment primary key column to a placeholder.
    primaryKeyBuilder.addPrimaryKeyColumn("incr", PrimaryKeyValue.AUTO_INCREMENT);
    PrimaryKey primaryKey = primaryKeyBuilder.build();

    // Construct the row data to write.
    RowPutChange rowPutChange = new RowPutChange("test_table", primaryKey);
    rowPutChange.addColumn("col1", ColumnValue.fromString("val1"));
    // Set the return type to RT_PK to return the primary key information of the written row.
    rowPutChange.setReturnType(ReturnType.RT_PK);

    // Call the putRow method to write the row of data.
    PutRowRequest putRowRequest = new PutRowRequest();
    putRowRequest.setRowChange(rowPutChange);
    PutRowResponse putRowResponse = client.putRow(putRowRequest);

    // Display the request Id and read/write CU consumption.
    System.out.println("RequestId: " + putRowResponse.getRequestId());
    System.out.println("Read CU Cost: " + putRowResponse.getConsumedCapacity().getCapacityUnit().getReadCapacityUnit());
    System.out.println("Write CU Cost: " + putRowResponse.getConsumedCapacity().getCapacityUnit().getWriteCapacityUnit());

    // Obtain and print the returned primary key information. If the return type is not set to RT_PK, the primary key information is not returned.
    Row row = putRowResponse.getRow();
    if(row != null)
        System.out.println(row.getPrimaryKey().toString());
}