For information on how to get started with Apache Ignite, please visit: Getting Started.
You can find the full Apache Ignite documentation here: Full documentation.
What is Apache Ignite?
Apache Ignite is a memory-centric distributed database, caching, and processing platform for transactional, analytical, and streaming workloads delivering in-memory speeds at petabyte scale.
Apache Ignite is based on distributed memory-centric architecture that combines the performance and scale of in-memory computing together with the disk durability and strong consistency in one system.
The main difference between the memory-centric approach and the traditional disk-centric approach is that the memory is treated as a fully functional storage, not just as a caching layer, like most databases do. For example, Apache Ignite can function in a pure in-memory mode, in which case it can be treated as an In-Memory Database (IMDB) and In-Memory Data Grid (IMDG) in one.
On the other hand, when persistence is turned on, Ignite begins to function as a memory-centric system where most of the processing happens in memory, but the data and indexes get persisted to disk. The main difference here from the traditional disk-centric RDBMS or NoSQL system is that Ignite is strongly consistent, horizontally scalable, and supports both SQL and key-value processing APIs.
Ignite Native Persistence is a distributed, ACID, and SQL-compliant disk store that transparently integrates with Ignite memory-centric storage as an optional disk layer storing data and indexes on SSD, Flash, 3D XPoint, and other types of non-volatile storages.
With the Ignite Persistence enabled, you no longer need to keep all the data and indexes in memory or warm it up after a node or cluster restart because the Durable Memory is tightly coupled with persistence and treats it as a secondary memory tier. This implies that if a subset of data or an index is missing in RAM, the Durable Memory will take it from the disk.
Data stored in Ignite is ACID-compliant both in memory and on disk, making Ignite a strongly consistent system. Ignite transactions work across the network and can span multiple servers.
Complete SQL Support
Ignite provides full support for SQL, DDL and DML, allowing users to interact with Ignite using pure SQL without writing any code. This means that users can create tables and indexes as well as insert, update, and query data using only SQL. Having such complete SQL support makes Ignite a one-of-a-kind distributed SQL database.
The in-memory data grid component in Ignite is a fully transactional distributed key-value store that can scale horizontally across 100s of servers in the cluster. When persistence is enabled, Ignite can also store more data than fits in memory and survive full cluster restarts.
Most traditional databases work in a client-server fashion, meaning that data must be brought to the client side for processing. This approach requires lots of data movement from servers to clients and generally does not scale. Ignite, on the other hand, allows for sending light-weight computations to the data, i.e. collocating computations with data. As a result, Ignite scales better and minimizes data movement.
Scalability and Durability
Ignite is an elastic, horizontally scalable distributed system that supports adding and removing cluster nodes on demand. Ignite also allows for storing multiple copies of the data, making it resilient to partial cluster failures. If the persistence is enabled, then data stored in Ignite will also survive full cluster failures. Cluster restarts in Ignite can be very fast, as the data becomes operational instantaneously directly from disk. As a result, the data does not need to be preloaded in-memory to begin processing, and Ignite caches will lazily warm up resuming the in memory performance.
You can view Apache Ignite as a collection of independent, well-integrated components geared to improve performance and scalability of your application.
Some of these components include:
- Advanced Clustering
- Data Grid
- SQL Database
- Compute Grid
- Service Grid
- Hadoop Accelerator
- Spark Shared RDDs and SQL indexes
Below you’ll find a brief explanation for each of them.
Ignite nodes can automatically discover each other. This helps to scale the cluster when needed, without having to restart the whole cluster. Developers can also leverage from Ignite’s hybrid cloud support that allows establishing connection between private cloud and public clouds such as Amazon Web Services, providing them with best of both worlds.
Apache Ignite can be deployed on:
Data Grid (JCache)
Ignite data grid is an in-memory distributed key-value store which can be viewed as a distributed partitioned hash map, with every cluster node owning a portion of the overall data. This way the more cluster nodes we add, the more data we can cache.
Unlike other key-value stores, Ignite determines data locality using a pluggable hashing algorithm. Every client can determine which node a key belongs to by plugging it into a hashing function, without a need for any special mapping servers or name nodes.
Ignite data grid supports local, replicated, and partitioned data sets and allows to freely cross query between these data sets using standard SQL syntax. Ignite supports standard SQL for querying in-memory data including support for distributed SQL joins.
Apache Ignite incorporates distributed SQL database capabilities as a part of its platform. The database is horizontally scalable, fault tolerant and SQL ANSI-99 compliant. It supports all SQL, DDL, and DML commands including SELECT, UPDATE, INSERT, MERGE, and DELETE queries. It also provides support for a subset of DDL commands relevant for distributed databases.
With Ignite Durable Memory architecture, data as well as indexes can be stored both in memory and, optionally, on disk. This allows executing distributed SQL operations across different memory layers achieving in-memory performance with the durability of disk.
You can interact with Apache Ignite using the SQL language via natively developed APIs for Java, .NET and C++, or via the Ignite JDBC or ODBC drivers. This provides a true cross-platform connectivity from languages such as PHP, Ruby and more.
Distributed computations are performed in parallel fashion to gain high performance, low latency, and linear scalability. Ignite compute grid provides a set of simple APIs that allow users distribute computations and data processing across multiple computers in the cluster. Distributed parallel processing is based on the ability to take any computation and execute it on any set of cluster nodes and return the results back.
We support these features, amongst others:
- Distributed Closure Execution
- MapReduce & ForkJoin Processing
- Continuous Mapping
- Clustered Executor Service
- Per-Node Shared State
- Collocation of Compute and Data
- Load Balancing
- Fault Tolerance
- Job State Checkpointing
- Job Scheduling
Service Grid allows for deployments of arbitrary user-defined services on the cluster. You can implement and deploy any service, such as custom counters, ID generators, hierarchical maps, etc.
Ignite allows you to control how many instances of your service should be deployed on each cluster node and will automatically ensure proper deployment and fault tolerance of all the services.
Ignite File System
Ignite File System (IGFS) is an in-memory file system allowing work with files and directories over existing cache infrastructure. IGFS can either work as purely in-memory file system, or delegate to another file system (e.g. various Hadoop file system implementations) acting as a caching layer.
In addition, IGFS provides API to execute map-reduce tasks over file system data.
Distributed Data Structures
Ignite supports complex data structures in a distributed fashion:
- Queues and sets: ordinary, bounded, collocated, non-collocated
- Atomic types:
- ID Generators
Distributed messaging allows for topic based cluster-wide communication between all nodes. Messages with a specified message topic can be distributed to all or sub-group of nodes that have subscribed to that topic.
Ignite messaging is based on publish-subscribe paradigm where publishers and subscribers are connected together by a common topic. When one of the nodes sends a message A for topic T, it is published on all nodes that have subscribed to T.
Distributed events allow applications to receive notifications when a variety of events occur in the distributed grid environment. You can automatically get notified for task executions, read, write or query operations occurring on local or remote nodes within the cluster.
Our Hadoop Accelerator provides a set of components allowing for in-memory Hadoop job execution and file system operations.
An alternate high-performant implementation of job tracker which replaces standard Hadoop MapReduce. Use it to boost your Hadoop MapReduce job execution performance.
IGFS - In-Memory File System
A Hadoop-compliant IGFS File System implementation over which Hadoop can run over in plug-n-play fashion and significantly reduce I/O and improve both, latency and throughput.
Secondary File System
An implementation of
SecondaryFileSystem. This implementation can be injected into existing IGFS allowing for
read-through and write-through behavior over any other Hadoop FileSystem implementation (e.g. HDFS). Use it if you
want your IGFS to become an in-memory caching layer over disk-based HDFS or any other Hadoop-compliant file system.
Supported Hadoop distributions
Spark Shared RDDs
Apache Ignite provides an implementation of Spark RDD abstraction which allows to easily share state in memory across Spark jobs.
The main difference between native Spark
IgniteRDD is that Ignite RDD provides a shared in-memory view on data across different Spark jobs, workers, or applications, while native Spark RDD cannot be seen by other Spark jobs or applications.
Is Ignite a persistent or pure in-memory storage?
Both. Native persistence in Ignite can be turned on and off. This allows Ignite to store data sets bigger than can fit in the available memory. Essentially, the smaller operational data sets can be stored in-memory only, and larger data sets that do not fit in memory can be stored on disk, using memory as a caching layer for better performance.
Is Ignite a distributed database?
Yes. Data in Ignite is either partitioned or replicated across a cluster of multiple nodes. This provides scalability and adds resilience to the system. Ignite automatically controls how data is partitioned, however, users can plug in their own distribution (affinity) functions and collocate various pieces of data together for efficiency.
Is Ignite a relational SQL database?
Not fully. Although Ignite aims to behave like any other relational SQL database, there are differences in how Ignite handles constraints and indexes. Ignite supports primary and secondary indexes, however, the uniqueness can only be enforced for the primary indexes. Ignite also does not support foreign key constraints.
Essentially, Ignite purposely does not support any constraints that would entail a cluster broadcast message for each update and significantly hurt performance and scalability of the system.
Is Ignite an in-memory database?
Yes. Even though Ignite durable memory works well in-memory and on-disk, the disk persistence can be disabled and Ignite can act as a pure in-memory database.
Is Ignite a transactional database?
Not fully. ACID Transactions are supported, but only at key-value API level. Ignite also supports cross-partition transactions, which means that transactions can span keys residing in different partitions on different servers.
At SQL level Ignite supports atomic, but not yet transactional consistency. Ignite community plans to implement SQL transactions in version 2.2.
Is Ignite a key-value store?
Yes. Ignite provides a feature rich key-value API, that is JCache (JSR-107) compliant and supports Java, C++, and .NET.
Is Ignite an in-memory data grid?
Yes. Ignite is a full-featured data grid, which can be used either in pure in-memory mode or with Ignite native persistence. It can also integrate with any 3rd party database, including any RDBMS or NoSQL store.
What is durable memory?
Ignite durable memory architecture allows Ignite to extend in-memory computing to disk. It is based on a paged-based off-heap memory allocator which becomes durable by persisting to the write-ahead-log (WAL) and, then, to main Ignite persistent storage. When persistence is disabled, durable memory acts like a pure in-memory storage.
What is collocated processing?
Ignite is a distributed system and, therefore, it is important to be able to collocate data with data and compute with data to avoid distributed data noise. Data collocation becomes especially important when performing distributed SQL joins. Ignite also supports sending user logic (functions, lambdas, etc.) directly to the nodes where the data resides and computing on the data locally.