Apache Ignite™ is ...

the in-memory computing platform
that is durable, strongly consistent, and highly available
with powerful SQLkey-value and processing APIs

Apache Ignite - Durable Memory

Durable Memory

Ignite's durable memory component treats RAM not just as a caching layer but as a complete fully functional storage layer. This means that users can turn the persistence on and off as needed. If the persistence is off, then Ignite can act as a distributed in-memory database or in-memory data grid, depending on whether you prefer to use SQL or key-value APIs. If the persistence is turned on, then Ignite becomes a distributed, horizontally scalable database that guarantees full data consistency and is resilient to full cluster failures.

Ignite Persistence

Ignite native persistence is a distributed, strongly consistent disk store that transparently integrates with Ignite's durable memory.

ACID Compliance

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.

Collocated Processing

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.

Ignite Facts

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 an in-memory database (IMDB)?

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 distributed in-memory database, with support for SQL and distributed joins.

Is Ignite an in-memory data grid (IMDG)?

Yes. Ignite is a full-featured distributed key-value data grid, which can be used either in pure in-memory mode or with Ignite native persistence. It can also automatically integrate with any 3rd party databases, including any RDBMS or NoSQL stores.

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 resiliency to the system. Ignite automatically controls how data is partitioned, however, users can plugin their own distribution (affinity) functions and collocate various pieces of data together for efficiency.

Is Ignite an 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 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 2.4.

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.


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