What's new in Apache Ignite.NET 1.9

Apache Ignite 1.9 has been released last week. Let’s see what is new in the .NET part.

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TransactionScope API

Before 1.9, Ignite transactions could only be started explicitly with IIgnite.GetTransactions().TxStart() call.

Now you can also use standard TransactionScope API:

using (var ts = new TransactionScope())
{
  cache[1] = 2;
  cache[2] = 1;

  // Transaction has been started on first transactional ICache method call.
  Debug.Assert(ignite.GetTransactions().Tx != null);

  ts.Complete();
}

Besides being easier to use, TransactionScope API allows performing transactional operations across multiple systems (via Two Phase Commit). For example, you can update SQL Server database and Ignite cache within a single TransactionScope block. All operations will participate in a common transaction, so that either both systems are updated, or all changes are reverted.

Documentation page: apacheignite-net.readme.io/docs/transactionscope-api

Distributed DML

In previous versions, Ignite SQL worked only in data retrieval mode (SELECT statements). Data Manipulation Language statements (INSERT, UPDATE, DELETE, MERGE) support has been added in 1.9 via existing QueryFields API:

// Insert person as object:
cache.QueryFields(new SqlFieldsQuery("INSERT INTO Person(_key, _val) VALUES(?, ?)", 1L, new Person("John", "Smith")));

// Insert person as fields:
cache.QueryFields(new SqlFieldsQuery(
    "INSERT INTO Person(_key, firstName, lastName) VALUES(?, ?, ?)", 1L, "John", "Smith"));

These statements are translated to ICache.Put() and ICache.InvokeAll() calls.

Documentation page: apacheignite-net.readme.io/docs/distributed-dml

LINQ Improvements

Distributed LINQ continues to evolve:

Contains

IEnumerable.Contains extension method is now supported:

var persons = ignite.GetCache<int, Person>("persons").AsCacheQueryable();

// Select persons with specific ids using inline collection:
var res = cache.Select(x => x.Value).Where(p => new[] {1, 2, 3}.Contains(p.Id));

// Generated SQL:
// select _T0._val from "persons".Person as _T0 where (_T0.Id IN (?, ?, ?))

Keep in mind that queries with IN clause are not always optimal: apacheignite-net.readme.io/docs/sql-queries#section-performance-and-usability-considerations.

DateTime Properties

The following DateTime properties can be used in LINQ: Year, Month, Day, Hour, Minute, Second, DayOfYear, DayOfWeek.

var persons = ignite.GetCache<int, Person>("persons").AsCacheQueryable();

// Find people born on Programmers` Day:
var res = persons.Where(x => x.Value.BirthDay.DayOfYear == 0x100);

// Generated SQL:
// select _T0._key, _T0._val from "persons".Person as _T0 where (day_of_year(_T0.BirthDay) = ?)

Inline Joins

Previous limitation where you had to have a separate variable for joined caches no longer exists:

// Before:
var roles = GetRoleCache().AsCacheQueryable();
var res = GetPersonCache().AsCacheQueryable().Join(roles, 
                person => person.Key, role => role.Key.Foo, (person, role) => role).ToArray();

// After:
var res = GetPersonCache().AsCacheQueryable().Join(GetRoleCache().AsCacheQueryable(), 
                person => person.Key, role => role.Key.Foo, (person, role) => role).ToArray();

// Query syntax:
var res =
          from person in GetPersonCache().AsCacheQueryable()
          from role in GetRoleCache().AsCacheQueryable()
          where person.Key == role.Key.Foo
          select new {Person = person.Value.Name, Role = role.Value.Name};

Written on March 14, 2017