This topic describes how to configure an auto-increment primary key column. You cannot set a partition key to an auto-increment column. If you write data to a table that contains an auto-increment primary key column, you do not need to specify specific values for the auto-increment primary key column because Tablestore generates values for the auto-increment primary key column. Values generated for the auto-increment primary key column are unique and consecutive within the partition that shares the same partition key value.

Prerequisites

Client is initialized. For more information, see Initialization.

Usage notes

  1. When you create a table, you cannot set the partition key to an auto-increment primary key column.

    The data type of an auto-increment primary key column can only be set to integer. Each value generated for an auto-increment primary key column is a 64-bit signed long integer.

  2. When you write data to a table, you do not need to set specific values for the auto-increment column. You need only to set placeholder values for the auto-increment column.

    If you want to obtain the values of the auto-increment column after data is written to the table, you can set ReturnType to RT_PK.

    When you query data, you must specify the values of all primary key columns. To obtain a complete primary key value, you can set ReturnType to RT_PK in PutRow, UpdateRow, or BatchWriteRow.

Examples

When you use auto-increment primary key columns, you can call the CreateTable, PutRow, UpdateRow, or BatchWriteRow operation.
  • To create an auto-increment primary key column when you create a table, you must set the attribute of the primary key column to AUTO_INCREMENT.
  • When you write data to a table, you do not need to set specific values for the auto-increment primary key column. You need only to set placeholder values for the column. 
using System;
using System.Collections.Generic;
using Aliyun.OTS.DataModel;
using Aliyun.OTS.Request;
using Aliyun.OTS.Response;

namespace Aliyun.OTS.Samples.Samples
{
    /// <summary>
    /// Example: Create an auto-increment primary key column.
    /// </summary>
    public class AutoIncrementSample
    {
        private static readonly string TableName = "AutoIncrementSample";

        private static readonly string Pk1 = "Pk1";
        private static readonly string Pk2 = "Pk2_AutoIncrement";


        static void Main(string[] args)
        {
            Console.WriteLine("AutoIncrementSample");

            // Create a table that contains an auto-increment column.
            CreateTableWithAutoIncrementPk();

            // Write 10 rows of data.
            for (int i = 0; i < 10; i++)
            {  
                PutRow(i.ToString());
            }

            Console.ReadLine();

        }

        /// <summary>
        /// Create a table that contains an auto-increment column.
        /// </summary>
        private static void CreateTableWithAutoIncrementPk()
        {

            OTSClient otsClient = Config.GetClient();

            IList<string> tables = otsClient.ListTable(new ListTableRequest()).TableNames;
            if (tables.Contains(TableName))
            {
                return;
            }

            PrimaryKeySchema primaryKeySchema = new PrimaryKeySchema
            {
                { Pk1, ColumnValueType.String },
                // Set Pk2 to the auto-increment column.
                { Pk2, ColumnValueType.Integer, PrimaryKeyOption.AUTO_INCREMENT}
            };
            TableMeta tableMeta = new TableMeta(TableName, primaryKeySchema);

            CapacityUnit reservedThroughput = new CapacityUnit(0, 0);
            CreateTableRequest request = new CreateTableRequest(tableMeta, reservedThroughput);
            otsClient.CreateTable(request);

        }

        public static void PutRow(string pk1Value)
        {
            Console.WriteLine("Start put row...") ;
            OTSClient otsClient = Config.GetClient();

            // Specify the primary keys of the row. These primary keys must be consistent with those specified in TableMeta when you create the table.
            PrimaryKey primaryKey = new PrimaryKey
            {
                { Pk1, new ColumnValue(pk1Value) },
                { Pk2,  ColumnValue.AUTO_INCREMENT }
            };

            // Specify the attribute columns of the row.
            AttributeColumns attribute = new AttributeColumns
            {
                { "Col1", new ColumnValue(0) }
            };
            PutRowRequest request = new PutRowRequest(TableName, new Condition(RowExistenceExpectation.IGNORE), primaryKey, attribute);
            request.RowPutChange.ReturnType = ReturnType.RT_PK;

            var response =  otsClient.PutRow(request);
            Console.WriteLine("Put row succeed, autoIncrement Pk value:"+ response.Row.GetPrimaryKey()[Pk2].IntegerValue);
        }

    }
}