This topic describes how to create a data table by calling the CreateTable operation. When you call the CreateTable operation, you must specify the schema information and configuration information of the data table when you call the CreateTable operation. You can set reserved read throughput and reserved write throughput for data tables in high-performance instances. You can create one or more index tables when you create a data table.

Note
  • After a table is created, it takes several seconds to load the table. During this period, the read and write operations performed on the table may fail. Perform operations on a table after the table is loaded.
  • You must specify the primary key when you create a table. A primary key can contain one to four primary key columns. Each primary key column has a name and a data type.

Prerequisites

  • An instance is created in the Tablestore console. For more information, see Create instances.
  • Client is initialized. For more information, see Initialization.

Parameters

Parameter Description
tableMeta The schema information of the data table. The schema information contains the following items:
  • tableName: the name of the data table.
  • primaryKey: the schema of the primary key for the data table. For more information, see Primary keys and attributes.
    Note Attribute columns are optional. Different rows in Tablestore can have different attribute columns. You can specify the names of attribute columns when you write data to the attribute columns.
    • The primary key of a data table can contain one to four primary key columns. Primary key columns are sorted in the order in which they are added. For example, PRIMARY KEY (A, B, C) and PRIMARY KEY (A, C, B) have different primary key schemas. Tablestore sorts rows based on the values of all primary key columns.
    • The first primary key column serves as the partition key. Data that has the same partition key value is stored in the same partition. Therefore, we recommend that you assign no more than 10 GB of data to partitions that have the same partition key value. Otherwise, a single partition may be too large to split. We recommend that you evenly distribute requests to read and write data to partitions that have different partition keys for load balancing.
  • definedColumns: the predefined columns of the table and the data types of the predefined column values. Primary key columns cannot be specified as predefined columns. You can use predefined columns as the indexed columns or attribute columns for index tables.
tableOptions The configuration information of the data table. For more information, see Max versions and TTL.

The configurations include the following items:

  • timeToLive: the period for which data in the data table can be retained. This period is the validity period of data. When the retention period exceeds the timeToLive value, Tablestore automatically deletes expired data.

    The minimum timeToLive is 86400, which is equal to one day. A value of -1 specifies that data never expires.

    When you create a data table, you can set timeToLive to -1 if you expect that data never expires. After the table is created, you can call the UpdateTable operation to modify the timeToLive value.

    Unit: seconds.

    Note You must set timeToLive to -1 if you want to create an index table for a data table.
  • maxVersions: the maximum number of versions of data that can be retained for a single attribute column. When the number of versions of data in attribute columns exceeds the maxVersions value, Tablestore automatically deletes the data of earlier versions.

    When you create a data table, you can customize the maximum number of versions that can be retained for the data in an attribute column. After the data table is created, you can call the UpdateTable operation to modify the maxVersions value for the data table.

    Note You must set maxVersions to 1 if you want to create an index table for a data table.
  • maxTimeDeviation: the max version offset, which is the maximum difference between the timestamp of the written data and the current system time. The difference between the version number and the data written time must be within the value of maxTimeDeviation. Otherwise, an error occurs when the data is written. Unit: seconds.

    The valid version range of data in an attribute column is calculated based on the formula: Valid version range = [Data written time - Max version offset, Data written time + Max version offset).

    When you create a data table, Tablestore uses the default value of 86400 if you do not specify a max version offset. After the data table is created, you can call the UpdateTable operation to modify the max version offset value.

    Unit: seconds.

reservedThroughtput The reserved read throughput and reserved write throughput of the data table.

The reserved read throughput and reserved write throughput can be set to 0 for data tables only in capacity instances. Reserved throughput does not apply to these instances.

The default value 0 specifies that all throughput is billed on a pay-as-you-go basis.

Unit: capacity unit (CU).

  • If reserved read throughput or reserved write throughput is set to a value greater than 0 for a data table, Tablestore allocates and reserves related resources for the data table. After the data table is created, Tablestore charges reserved throughput resources. Additional throughput is billed on a pay-as-you-go basis. For more information, see Billing overview.
  • If reserved read throughput or reserved write throughput is set to 0, Tablestore does not allocate or reserve related resources for the table.
indexMetas The schema information of the index tables. Each indexMeta contains the following items:
  • indexName: the name of the index table.
  • primaryKey: the indexed columns of the index table. The indexed columns are a combination of primary key columns and predefined columns of the data table.

    If you use the local secondary index feature, the first primary key column of an index table must be the same as the first primary key column of the corresponding data table.

  • definedColumn: the indexed attribute columns. The attribute columns are a combination of predefined columns of the data table.
  • indexType: the type of the index. Valid values: IT_GLOBAL_INDEX and IT_LOCAL_INDEX.
    • If indexType is not specified or is set to IT_GLOBAL_INDEX, the global secondary index feature is used.

      If you use the global secondary index feature, Tablestore automatically synchronizes the columns to index and data in primary key columns from a data table to an index table in asynchronous mode. The synchronization latency is within a few milliseconds.

    • If indexType is set to IT_LOCAL_INDEX, the local secondary index feature is used.

      If you use the local secondary index feature, Tablestore automatically synchronizes data from the indexed columns and the primary key columns of a data table to the columns of an index table in synchronous mode. After the data is written to the data table, you can query the data from the index table.

  • indexUpdateMode: the update mode of the global secondary index. Valid values: IUM_ASYNC_INDEX and IUM_SYNC_INDEX.
    • If indexUpdateMode is not specified or set to IUM_ASYNC_INDEX, the asynchronous mode is used to update the global secondary index.

      If you use the global secondary index feature, you must set the index update mode to IUM_ASYNC_INDEX.

    • If you set indexUpdateMode to IUM_SYNC_INDEX, the synchronous update mode is used.

      If you use the local secondary index feature, you must set the update mode to IUM_SYNC_INDEX.

Examples

  • Create a data table without creating an index table 
    private static void createTable(SyncClient client) {
        TableMeta tableMeta = new TableMeta(TABLE_NAME);
        tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema(PRIMARY_KEY_NAME, PrimaryKeyType.STRING)); // Specify a primary key column for the data table. 
        int timeToLive = -1; // Specify the validity period of data. A value of -1 specifies that the data never expires. Unit: seconds. You must set timeToLive to -1 for a data table that has index tables. 
        int maxVersions = 3; // Specify the maximum number of versions that can be retained for each column. A value of 1 specifies that only the latest version is retained for each column. You must set maxVersions to 1 if you want to create an index table for a data table. 
        TableOptions tableOptions = new TableOptions(timeToLive, maxVersions);
        CreateTableRequest request = new CreateTableRequest(tableMeta, tableOptions);
        request.setReservedThroughput(new ReservedThroughput(new CapacityUnit(0, 0))); // Set the reserved read throughput and reserved write throughout. The reserved read throughput and reserved write throughput can be set to 0 for data tables only in capacity instances. However, you can set a non-zero value for data tables in high-performance instances. 
        client.createTable(request);
}
  • Create a data table and an index table whose index type is global secondary index 
    private static void createTable(SyncClient client) {
    TableMeta tableMeta = new TableMeta(TABLE_NAME);
    tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema(PRIMARY_KEY_NAME_1, PrimaryKeyType.STRING)); // Add a primary key column to the data table. 
    tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema(PRIMARY_KEY_NAME_2, PrimaryKeyType.INTEGER)); // Add a primary key column to the data table. 
    tableMeta.addDefinedColumn(new DefinedColumnSchema(DEFINED_COL_NAME_1, DefinedColumnType.STRING)); // Add a predefined column to the data table. 
    tableMeta.addDefinedColumn(new DefinedColumnSchema(DEFINED_COL_NAME_2, DefinedColumnType.INTEGER)); // Add a predefined column to the data table. 

    int timeToLive = -1; // Specify the validity period of data. A value of -1 specifies that the data never expires. Unit: seconds. You must set timeToLive to -1 for a data table that has index tables. 
    int maxVersions = 1; // Specify the maximum number of versions that can be retained for each column. A value of 1 specifies that only the latest version is retained for each column. You must set maxVersions to 1 if you want to create an index table for a data table. 

    TableOptions tableOptions = new TableOptions(timeToLive, maxVersions);

    ArrayList<IndexMeta> indexMetas = new ArrayList<IndexMeta>();
    IndexMeta indexMeta = new IndexMeta(INDEX_NAME);
    indexMeta.addPrimaryKeyColumn(DEFINED_COL_NAME_1); // Add a primary key column to the index table. 
    indexMeta.addDefinedColumn(DEFINED_COL_NAME_2); // Add an attribute column to the index table. 
    indexMetas.add(indexMeta);

    CreateTableRequest request = new CreateTableRequest(tableMeta, tableOptions, indexMetas); // Create the index table when you create the data table. 

    client.createTable(request);
}
  • Create a data table and an index table whose index type is local secondary index 
    private static void createTable(SyncClient client) {
    TableMeta tableMeta = new TableMeta(TABLE_NAME);
    tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema(PRIMARY_KEY_NAME_1, PrimaryKeyType.STRING)); // Add a primary key column to the data table. 
    tableMeta.addPrimaryKeyColumn(new PrimaryKeySchema(PRIMARY_KEY_NAME_2, PrimaryKeyType.INTEGER)); // Add a primary key column to the data table. 
    tableMeta.addDefinedColumn(new DefinedColumnSchema(DEFINED_COL_NAME_1, DefinedColumnType.STRING)); // Add a predefined column to the data table. 
    tableMeta.addDefinedColumn(new DefinedColumnSchema(DEFINED_COL_NAME_2, DefinedColumnType.INTEGER)); // Add a predefined column to the data table. 

    int timeToLive = -1; // Specify the validity period of data. A value of -1 specifies that the data never expires. Unit: seconds. You must set timeToLive to -1 for a data table that has index tables. 
    int maxVersions = 1; // Specify the maximum number of versions that can be retained for each column. A value of 1 specifies that only the latest version is retained for each column. You must set maxVersions to 1 if you want to create an index table for a data table. 

    TableOptions tableOptions = new TableOptions(timeToLive, maxVersions);

    ArrayList<IndexMeta> indexMetas = new ArrayList<IndexMeta>();
    IndexMeta indexMeta = new IndexMeta(INDEX_NAME);
    indexMeta.setIndexType(IT_LOCAL_INDEX);     // Set the index type to IT_LOCAL_INDEX, which specifies a local secondary index. 
    indexMeta.setIndexUpdateMode(IUM_SYNC_INDEX);  // Set the index update mode to IUM_SYNC_INDEX, which specifies the synchronous update mode. If the index type is set to IT_LOCAL_INDEX, the index update mode must be set to IUM_SYNC_INDEX. 

    indexMeta.addPrimaryKeyColumn(PRIMARY_KEY_NAME_1); // Add a primary key column to the index table. The first primary key column of the index table must be the same as that of the data table. 
    indexMeta.addPrimaryKeyColumn(DEFINED_COL_NAME_1); // Add a primary key column to the index table. 
    indexMeta.addDefinedColumn(DEFINED_COL_NAME_2); // Add an attribute column to the index table. 
    indexMetas.add(indexMeta);

    CreateTableRequest request = new CreateTableRequest(tableMeta, tableOptions, indexMetas); // Create the index table when you create the data table. 

    client.createTable(request);
}