GridGain Developers Hub

Table API

To execute table operations on a specific table, you need to get a specific view of the table and use one of its methods. You can only create new tables by using SQL API.

GridGain supports mapping user objects to table tuples. This ensures that objects created in any programming language can be used for key-value operations directly.

Table Views in GridGain 9

Data Representation: Tuples vs POJOs/Records

When working with tables, GridGain offers two approaches: directly handling the data or mapping the data to classes. The direct data handling approach handles data tuples. Alternatively, when mapping data to classes, the data is converted to and from these classes as needed for database interactions.

View Types: RecordView vs KeyValueView

When creating views, you can create a RecordView or KeyValueView. The primary difference between these view types is the API used.

In a RecordView, you create a single “record” that includes all the information about a row to be updated or retrieved from the table, and send this record to the server. This record should contain all the fields, including the primary key.

In a KeyValueView, you work with key-value mappings. Think of it as a dictionary where the key object contains the primary key field or fields, and the value object contains the data fields. This approach is useful when primary key is not directly related to the domain object thus you prefer not to add the primary key to it.

Data Type Support

Time and Date Data Types

Only JavaTime API is supported for working with table views. The following data types are not supported:

  • java.util.Date

  • java.sql.Date

  • java.sql.Time

  • java.sql.Timestamp

Use the following data types instead:

  • java.time.LocalDate

  • java.time.LocalTime

  • java.time.LocalDateTime

  • java.time.Instant

Getting a Table Instance

First, get an instance of the table. To obtain an instance of table, use the IgniteTables.table(String) method. You can also use IgniteTables.tables() method to list all existing tables.

IgniteTables tableApi = client.tables();
List<Table> existingTables = tableApi.tables();
Table firstTable = existingTables.get(0);
var existingTables = await Client.Tables.GetTablesAsync();
var firstTable = existingTables[0];

var myTable = await Client.Tables.GetTableAsync("MY_TABLE");
using namespace ignite;

auto table_api = client.get_tables();
std::vector<table> existing_tables = table_api.get_tables();
table first_table = existing_tables.front();

std::optional<table> my_table = table_api.get_table("MY_TABLE);

By default, if the schema name is not specified, the PUBLIC schema is used. If a qualified name is specified, the table is taken from the specified schema.

Qualified Table Name Object

Instead of using a string to specify table name, you can create a QualifiedName object to hold a fully qualified table name. GridGain provides 2 methods for creating qualified names:

  • You can parse the fully qualified table name with the parse method:

    QualifiedName qualifiedTableName = QualifiedName.parse("PUBLIC.Person");
    Table myTable = tableApi.table(qualifiedTableName);
  • You can provide schema name and table name separately with the of method:

    QualifiedName qualifiedTableName = QualifiedName.of("PUBLIC", "MY_TABLE");
    Table myTable = tableApi.table(qualifiedTableName);

The provided names must follow SQL syntax rules for identifiers:

  • Identifier must start from a character in the “Lu”, “Ll”, “Lt”, “Lm”, “Lo”, or “Nl” Unicode categories or U+0331 (underscore);

  • Identifier characters (expect for the first one) may be U+00B7 (middle dot), or any character in the “Mn”, “Mc”, “Nd”, “Pc”, or “Cf” Unicode categories;

  • Identifiers that contain any other characters must be quoted with U+2033 (double-quotes);

  • Double-quote inside the identifier must be escaped with 2 double-quote characters.

Any unquoted names will be cast to upper case. In this case, Person and PERSON names are equivalent. To avoid this, add escaped quotes around the name. For example, \"Person\" will be encoded as a case-sensitive Person name. If the name contains the U+2033 (double quote) symbol, it must be escaped as "" (2 double quote symbols).

Foe example:

// Case-insensitive table `MY_TABLE` in a case-insensitive `PUBLIC` schema.
QualifiedName.parse("public.my_table"))

// Case-sensitive table `my_table` in a case-sensitive `public` schema.
QualifiedName.parse("\"public\".\"my_table\""))

// Same as above, but with comma as separator that needs to be surrounded by quote characters.
QualifiedName.of("\"public\"","\"my_table\""))

// Case-sensitive name my"table.
QualifiedName.parse("\"my\"\"table\""));

// Case-sensitive table name `public.my_table` in a default schema.
QualifiedName.parse("\"public.my_table\""));

Basic Table Operations

Once you’ve got a table you need to get a specific view to choose how you want to operate table records.

Tuple Record View

A tuple record view. It can be used to operate table tuples directly. When retrieving data from tuple views, you can use a wide variety of methods to retrieve type-specific data stored in tuples. A full list of methods is available in the Tuple object javadoc.


RecordView<Tuple> accounts = client.tables().table("accounts").recordView();


System.out.println("\nInserting a record into the 'accounts' table...");

Tuple newAccountTuple = Tuple.create()
        .set("accountNumber", 123456)
        .set("firstName", "John")
        .set("lastName", "Smith")
        .set("balance", 100.00d);

accounts.insert(null, newAccountTuple);


System.out.println("\nRetrieving a record using RecordView API...");

Tuple accountNumberTuple = Tuple.create().set("accountNumber", 123456);

Tuple accountTuple = accounts.get(null, accountNumberTuple);

System.out.println(
        "\nRetrieved record:\n"
                + "    Account Number: " + accountTuple.intValue("accountNumber") + '\n'
                + "    Owner: " + accountTuple.stringValue("firstName") + " " + accountTuple.stringValue("lastName") + '\n'
                + "    Balance: $" + accountTuple.doubleValue("balance"));
IRecordView<IIgniteTuple> view = table.RecordBinaryView;

IIgniteTuple fullRecord = new IgniteTuple
{
  ["id"] = 42,
  ["name"] = "John Doe"
};

await view.UpsertAsync(transaction: null, fullRecord);

IIgniteTuple keyRecord = new IgniteTuple { ["id"] = 42 };
(IIgniteTuple value, bool hasValue) = await view.GetAsync(transaction: null, keyRecord);

Debug.Assert(hasValue);
Debug.Assert(value.FieldCount == 2);
Debug.Assert(value["id"] as int? == 42);
Debug.Assert(value["name"] as string == "John Doe");
record_view<ignite_tuple> view = table.get_record_binary_view();

ignite_tuple record{
  {"id", 42},
  {"name", "John Doe"}
};

view.upsert(nullptr, record);
std::optional<ignite_tuple> res_record = view.get(nullptr, {"id", 42});

assert(res_record.has_value());
assert(res_record->column_count() == 2);
assert(res_record->get<std::int64_t>("id") == 42);
assert(res_record->get<std::string>("name") == "John Doe");

Record View

A record view maps to a user-defined type and enables table operations on user objects which are mapped to table tuples.

Create the type converter:

static class CityIdConverter implements TypeConverter<String, Integer> {

    @Override
    public String  toObjectType(Integer columnValue) {
        return columnValue.toString();
    }

    @Override
    public Integer toColumnType(String cityId) {
        return Integer.parseInt(cityId);
    }
}

Then build the mapper and get the RecordView:

public static void main(String[] args) throws Exception {
    var mapper = Mapper.builder(Person.class)
            .automap()
            .map("cityId", "city_id", new CityIdConverter())
            .build();

    try (IgniteClient client = IgniteClient.builder()
            .addresses("127.0.0.1:10800")
            .build()
    ) {
        RecordView<Person> view = client.tables()
                .table("person")
                .recordView(mapper);


        Person myPerson = new Person(2, "2", "John Doe", 40, "Apache");

        view.upsert(null, myPerson);
    }
}

Perform table operations on your custom objects mapped to table tuples:


RecordView<Account> accounts = client.tables()
        .table("accounts")
        .recordView(Account.class);

System.out.println("\nInserting a record into the 'accounts' table...");

Account newAccount = new Account(
        123456,
        "John",
        "Smith",
        100.00d
);

accounts.insert(null, newAccount);

System.out.println("\nRetrieving a record using RecordView API...");

Account account = accounts.get(null, new Account(123456));

System.out.println(
        "\nRetrieved record:\n"
            + "    Account Number: " + account.accountNumber + '\n'
            + "    Owner: " + account.firstName + " " + account.lastName + '\n'
            + "    Balance: $" + account.balance);
var pocoView = table.GetRecordView<Poco>();
await pocoView.UpsertAsync(transaction: null, new Poco(42, "John Doe"));
var (value, hasValue) = await pocoView.GetAsync(transaction: null, new Poco(42));

Debug.Assert(hasValue);
Debug.Assert(value.Name == "John Doe");

public record Poco(long Id, string? Name = null);
record_view<person> view = table.get_record_view<person>();

person record(42, "John Doe");

view.upsert(nullptr, record);
std::optional<person> res_record = view.get(nullptr, person{42});

assert(res.has_value());
assert(res->id == 42);
assert(res->name == "John Doe");

Key-Value Tuple View

A tuple key-value view. It can be used to operate table using key and value tuples separately. When retrieving data from tuple views, you can use a wide variety of methods to retrieve type-specific data stored in tuples. A full list of methods is available in the Tuple object javadoc.


KeyValueView<Tuple, Tuple> kvView = client.tables().table("accounts").keyValueView();


System.out.println("\nInserting a key-value pair into the 'accounts' table...");

Tuple key = Tuple.create()
        .set("accountNumber", 123456);

Tuple value = Tuple.create()
        .set("firstName", "John")
        .set("lastName", "Smith")
        .set("balance", 100.00d);

kvView.put(null, key, value);


System.out.println("\nRetrieving a value using KeyValueView API...");

value = kvView.get(null, key);

System.out.println(
        "\nRetrieved value:\n"
                + "    Account Number: " + key.intValue("accountNumber") + '\n'
                + "    Owner: " + value.stringValue("firstName") + " " + value.stringValue("lastName") + '\n'
                + "    Balance: $" + value.doubleValue("balance"));
IKeyValueView<IIgniteTuple, IIgniteTuple> kvView = table.KeyValueBinaryView;

IIgniteTuple key = new IgniteTuple { ["id"] = 42 };
IIgniteTuple val = new IgniteTuple { ["name"] = "John Doe" };

await kvView.PutAsync(transaction: null, key, val);
(IIgniteTuple? value, bool hasValue) = await kvView.GetAsync(transaction: null, key);

Debug.Assert(hasValue);
Debug.Assert(value.FieldCount == 1);
Debug.Assert(value["name"] as string == "John Doe");
key_value_view<ignite_tuple, ignite_tuple> kv_view = table.get_key_value_binary_view();

ignite_tuple key_tuple{{"id", 42}};
ignite_tuple val_tuple{{"name", "John Doe"}};

kv_view.put(nullptr, key_tuple, val_tuple);
std::optional<ignite_tuple> res_tuple = kv_view.get(nullptr, key_tuple);

assert(res_tuple.has_value());
assert(res_tuple->column_count() == 2);
assert(res_tuple->get<std::int64_t>("id") == 42);
assert(res_tuple->get<std::string>("name") == "John Doe");

Key-Value View

A key-value view with user objects. It can be used to operate table using key and value user objects mapped to table tuples.

KeyValueView<AccountKey, Account> kvView = client.tables()
        .table("accounts")
        .keyValueView(AccountKey.class, Account.class);
System.out.println("\nInserting a key-value pair into the 'accounts' table...");

AccountKey key = new AccountKey(123456);

Account value = new Account(
        "John",
        "Smith",
        100.00d
);

kvView.put(null, key, value);

System.out.println("\nRetrieving a value using KeyValueView API...");

value = kvView.get(null, key);


System.out.println(
        "\nRetrieved value:\n"
            + "    Account Number: " + key.accountNumber + '\n'
            + "    Owner: " + value.firstName + " " + value.lastName + '\n'
            + "    Balance: $" + value.balance);
IKeyValueView<long, Poco> kvView = table.GetKeyValueView<long, Poco>();

await kvView.PutAsync(transaction: null, 42, new Poco(Id: 0, Name: "John Doe"));
(Poco? value, bool hasValue) = await kvView.GetAsync(transaction: null, 42);

Debug.Assert(hasValue);
Debug.Assert(value.Name == "John Doe");

public record Poco(long Id, string? Name = null);
key_value_view<person, person> kv_view = table.get_key_value_view<person, person>();

kv_view.put(nullptr, {42}, {"John Doe"});
std::optional<person> res = kv_view.get(nullptr, {42});

assert(res.has_value());
assert(res->id == 42);
assert(res->name == "John Doe");

Working with Mappers

Mappers provide an abstraction layer that converts between your Java objects (POJOs or Records) and GridGain’s internal tuple representation. They eliminate the need to manually pack and unpack data, allowing you to work directly with your domain objects.

When you create a RecordView or KeyValueView with a POJO class, you can use a mapper to handle the conversion between your objects and table data.

There are two types of mappers:

  • PojoMapper: Maps individual object fields to columns (for POJOs and complex objects)

  • OneColumnMapper: Maps an entire object to a single column (for simple types)

Natively Supported Types

The following types are natively supported and can be used without custom type converters:

  • String

  • Boolean

  • UUID

  • byte[]

  • Numeric types: Byte, Short, Integer, Long, Float, Double, BigDecimal

  • Date/Time types: LocalDate, LocalTime, LocalDateTime, Instant

All other types require a custom type converter.

Creating Mappers

GridGain provides several ways to create mappers, from simple automatic mapping to fully customized configurations.

Automatic Class Mapping

You can use automatic class mapping to pass your POJO class directly to the view. GridGain automatically maps fields to columns by name:

RecordView<Account> accountView = table.recordView(Account.class);

// For KeyValueView
KeyValueView<AccountKey, AccountValue> kvView =
    table.keyValueView(AccountKey.class, AccountValue.class);

Factory Mapper Methods

For more advanced scenarios, use the static factory methods on the Mapper interface:

// Single column mapping
Mapper<String> nameMapper = Mapper.of(String.class, "name");
RecordView<String> nameView = table.recordView(nameMapper);

// Single column with type converter
Mapper<Status> statusMapper = Mapper.of(
    Status.class,
    "status",
    new StatusConverter()
);

// Explicit field-to-column pairs
Mapper<Person> customMapper = Mapper.of(
    Person.class,
    "id", "person_id",
    "fullName", "full_name",
    "age", "person_age"
);

Using MapperBuilder for Advanced Configuration

For complex mapping scenarios, use MapperBuilder:

Mapper<Person> mapper = Mapper.builder(Person.class)
    .map("fieldName", "column_name")
    .map("age", "person_age")
    .map("cityId", "city_id")
    .build();

RecordView<Person> view = table.recordView(mapper);

Mapping Options

Automatic Field Mapping with automap()

The automap() method automatically maps all object fields to columns with matching names:

Mapper<Person> mapper = Mapper.builder(Person.class)
    .automap()
    .build();

Behavior of automap():

  • Maps fields to columns with the same name in uppercase, consistently with SQL API.

  • Static and transient fields are automatically excluded.

  • Respects manual overriding (via .map() calls)

Example with using automap:

public class Person {
    private int id;           // Maps to ID column
    private String name;      // Maps to NAME column
    private int age;          // Maps to AGE column

    public Person() {}
}

Mapper<Person> mapper = Mapper.builder(Person.class)
    .automap()
    .build();

Explicit Mapping

When field names do not match column names, use explicit mapping:

Mapper<Person> mapper = Mapper.builder(Person.class)
    .map("fieldName", "column_name")
    .map("age", "person_age")
    .map("id", "person_id")
    .build();

You can also map multiple fields at once:

Mapper<Person> mapper = Mapper.builder(Person.class)
    .map("id", "person_id",
         "age", "person_age",
         "name", "person_name")
    .build();

Using @Column Annotation

You can use the @Column annotation to specify column names directly in your POJO:

import org.apache.ignite.catalog.annotations.Column;

public class Person {
    @Column("person_id")
    private int id;

    @Column("full_name")
    private String name;

    private int age;  // Maps to AGE by default

    public Person() {}
}

// Automatic mapping respects @Column annotations
Mapper<Person> mapper = Mapper.builder(Person.class)
    .automap()
    .build();

When mapped this way, column names specified in the annotation will be used.

Type Conversion

Type converters enable you to map fields whose types are incompatible with column types. They transform data when writing to and reading from the database.

The example below shows how you can map an object’s field of String type to a column of Integer type:

public class CityIdConverter implements TypeConverter<String, Integer> {
    @Override
    public String toObjectType(Integer columnValue) {
        return columnValue != null ? columnValue.toString() : null;
    }

    @Override
    public Integer toColumnType(String cityId) {
        return cityId != null ? Integer.parseInt(cityId) : null;
    }
}

// Use the converter
Mapper<Person> mapper = Mapper.builder(Person.class)
    .automap()
    .map("cityId", "city_id", new CityIdConverter())
    .build();

Java Records

You can also map tables to Java records.

Records behave identically to traditional classes when mapping to tables, with one key difference: the @Column annotation is applied to constructor parameters instead of fields.

Requirements

Java records require Java 14 or later.

RecordView with Records

The simplest way to use records is with RecordView. Annotate the record’s canonical constructor parameters with @Column:

public record Person(
    @Column("id") Integer id,
    @Column("name") String name,
    @Column("age") Integer age
) {}

public static void main(String[] args) {
    try (IgniteClient client = IgniteClient.builder()
            .addresses("127.0.0.1:10800")
            .build()
    ) {
        RecordView<Person> view = client.tables()
                .table("person")
                .recordView(Person.class);

        Person person = new Person(1, "John Doe", 30);
        view.upsert(null, person);

        Person retrieved = view.get(null, new Person(1, null, null));
        System.out.println("Retrieved: " + retrieved.name());
    }
}
KeyValueView with Records

You can use records for both keys and values in KeyValueView:

public record PersonKey(@Column("id") Integer id) {}

public record PersonValue(
    @Column("name") String name,
    @Column("age") Integer age
) {}

public static void main(String[] args) {
    try (IgniteClient client = IgniteClient.builder()
            .addresses("127.0.0.1:10800")
            .build()
    ) {
        KeyValueView<PersonKey, PersonValue> kvView = client.tables()
                .table("person")
                .keyValueView(PersonKey.class, PersonValue.class);

        PersonKey key = new PersonKey(1);
        PersonValue value = new PersonValue("John Doe", 30);

        kvView.put(null, key, value);

        PersonValue retrieved = kvView.get(null, key);
        System.out.println("Retrieved: " + retrieved.name());
    }
}
Creating Tables from Records

You can create tables directly from record definitions using the @Table annotation:

@Table(value = "person_table",
       zone = @Zone(value = "zone_default", replicas = 2, storageProfiles = "default"),
       indexes = @Index(value = "idx_name", columns = @ColumnRef("name")))
public record Person(
    @Id
    @Column("id") Integer id,

    @Column("name") String name,

    @Column(value = "age", nullable = true) Integer age
) {}

public static void main(String[] args) {
    try (IgniteClient client = IgniteClient.builder()
            .addresses("127.0.0.1:10800")
            .build()
    ) {
        org.apache.ignite.table.Table myTable =
            client.catalog().createTable(Person.class);

        RecordView<Person> view = myTable.recordView(Person.class);
        view.upsert(null, new Person(1, "John Doe", 30));
    }
}

For KeyValueView, provide both key and value record types:

@Table(value = "person_table",
       zone = @Zone(value = "zone_default", replicas = 2, storageProfiles = "default"))
public static class PersonKey {
    @Id
    @Column("id") Integer id;
}

public record PersonKeyRecord(@Column("id") Integer id) {}

public record PersonValueRecord(
    @Column("name") String name,
    @Column("age") Integer age
) {}

public static void main(String[] args) {
    try (IgniteClient client = IgniteClient.builder()
            .addresses("127.0.0.1:10800")
            .build()
    ) {
        // Create table using annotated class for schema definition
        org.apache.ignite.table.Table myTable =
            client.catalog().createTable(PersonKey.class, PersonValueRecord.class);

        // Use records for data operations
        KeyValueView<PersonKeyRecord, PersonValueRecord> kvView =
            myTable.keyValueView(PersonKeyRecord.class, PersonValueRecord.class);

        kvView.put(null,
                   new PersonKeyRecord(1),
                   new PersonValueRecord("John Doe", 30));
    }
}

Criterion Queries

GridGain 9 provides the criterion queries that can be used to retrieve data from tables. Criterion queries work with any type of view, returning the appropriate data to the query specified.

The example below shows how you can execute a query within an implicit transaction:

try (Cursor<Entry<Tuple, Tuple>> cursor = table.keyValueView().query(
        null, // Implicit transaction
        // Query criteria
        and(
                columnValue("name", equalTo("John Doe")),
                columnValue("age", greaterThan(20))
        )
)) {
    // Process query results (keeping original cursor iteration pattern)
    // As an example, println all matched values.
    while (cursor.hasNext()) {
        printRecord(cursor.next());
    }
}

The comparison query are specified by using the query() method, and providing the comparison criteria in the columnValue method.

You can also specify the specific transaction to execute the query in to perform the query in that specific transaction.

try (Cursor<Entry<Tuple, Tuple>> cursor = table.keyValueView().query(
        transaction,
        // Query criteria
        and(
                columnValue("name", equalTo("John Doe")),
                columnValue("age", greaterThan(20))
        )
)) {
    // Process query results
    // As an example, println all matched values.
    while (cursor.hasNext()) {
        printRecord(cursor.next());
    }

    // Commit transaction if all operations succeed
    transaction.commit();
} catch (Exception e) {
    // Rollback transaction on error
    transaction.rollback();
    throw new RuntimeException("Transaction failed", e);
}

Asynchronous Queries

You can also perform the query asynchronously by using the queryAsync method. This way the query is executed without blocking the thread. For example, you can execute the above query asynchronously:

public static void performQueryAsync(Table table) {
    System.out.println("[ Example 3 ] Performing asynchronous query");

    AsyncCursor<Entry<Tuple, Tuple>> result = table.keyValueView().queryAsync(
                    null, // Implicit transaction
                    and(
                            columnValue("name", equalTo("John Doe")),
                            columnValue("age", greaterThan(20))
                    )
            )
            .join();

    for (Entry<Tuple, Tuple> tupleTupleEntry : result.currentPage()) {
        printRecord(tupleTupleEntry);
    }
}

This operation uses the thenCompose() method to handle the query results asynchronously in the user-defined fetchAllRowsInto() method. Here is how this method may look like:

Table TTL

When inserting values to the table, you can set expiration time for these values if TTL is enabled in the table. You can set the TTL by using the CREATE TABLE or ALTER TABLE statements.

When adding data to the table, it is enough to put the desired TTL timestamp in the TTL column.

Comparison Expressions

The following expressions are supported in criterion queries:

Expression Description Example

equalTo

Checks if the object is equal to the value.

columnValue("City", equalTo("New York"))

notEqualTo

Checks if the object is not equal to the value.

columnValue("City", notEqualTo("New York"))

greaterThan

Checks if the object is greater than the value.

columnValue("Salary", greaterThan(10000))

greaterThanOrEqualTo

Checks if the object is greater than or equal to the value.

columnValue("Salary", greaterThanOrEqualTo(10000))

lessThan

Checks if the object is less than the value.

columnValue("Salary", lessThan(10000))

lessThanOrEqualTo

Checks if the object is less than or equal to the value.

columnValue("Salary", lessThanOrEqualTo(10000))

nullValue

Checks if the object is null.

columnValue("City", nullValue()

notNullValue

Checks if the object is not null.

columnValue("City", notNullValue())

in

Checks if the object is in the collection.

columnValue("City", in("New York", "Washington"))

notIn

Checks if the object is not in the collection.

columnValue("City", notIn("New York", "Washington"))

Comparison Operators

The following operators are supported in criterion queries:

Operator Description Example

not

Negates the condition.

not(columnValue("City", equalTo("New York")))

and

Used to evaluate multiple conditions at the same time.

and(columnValue("City", equalTo("New York")), columnValue("Salary", greaterThan(10000)))

or

Used to evaluate for at least one matching condition.

or(columnValue("City", equalTo("New York")), columnValue("Salary", greaterThan(10000)))

Partition API

To retrieve a partition id, you need to pass the corresponding key value and use the following method:

Table table = client.tables().table("PUBLIC.Person");
RecordView<Tuple> personTableView = table.recordView();


PartitionDistribution partDistribution = table.partitionDistribution();
Partition partition = partDistribution.partitionAsync(Tuple.create().set("id", 1)).join();

long partitionId = partition.id();
var table = await Client.Tables.GetTableAsync("PUBLIC.Person");
var partitionDistribution = table!.PartitionDistribution;
IPartition partition = await partitionDistribution.GetPartitionAsync(new IgniteTuple { ["id"] = 1 });
long partitionId = partition.Id;

As PartitionManager API is now deprecated and will be removed in upcoming releases, use PartitionDistribution API instead.

Table table = client.tables().table("PUBLIC.Person");
PartitionDistribution partDistribution = table.partitionDistribution();
var table = await Client.Tables.GetTableAsync("PUBLIC.Person");
var partitionDistribution = table!.PartitionDistribution;

For more details on data partitioning, see the following article.