## YugabyteDB

### What is YugabyteDB

YugabyteDB is a high-performant, highly available and scalable distributed SQL database designed for powering global, internet-scale applications. It is fully compatible with [PostgreSQL](https://www.postgresql.org/) and provides strong [ACID](/stable/architecture/key-concepts/#acid) guarantees for distributed transactions. It can be deployed in a single region, multi-region, and multi-cloud setups.

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Explore YugabyteDB
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### What makes YugabyteDB unique

YugabyteDB stands out as a unique database solution due to its combination of features that bring together the strengths of both traditional SQL databases and modern NoSQL systems. It is [horizontally scalable](/stable/explore/linear-scalability/), supports global geo-distribution, supports [SQL (YSQL)](/stable/api/ysql/sql-feature-support/) and [NoSQL (YCQL)](/stable/explore/ycql-language/) APIs, is [highly performant](/stable/benchmark/) and guarantees strong transactional consistency.

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Design goals
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### Is YugabyteDB open source?

YugabyteDB is 100% open source. It is licensed under Apache 2.0.

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Source code
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### How many major releases YugabyteDB has had so far?

YugabyteDB released its first beta, [v0.9](https://www.yugabyte.com/blog/yugabyte-has-arrived/) in November 2017. Since then, several stable and preview versions have been released. The current stable version is {{<release "stable">}}, and the current preview version is [v2.25.2.0](/stable/releases/ybdb-releases/end-of-life/v2.25/#v2.25.2.0).

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Releases
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### What is the difference between preview and stable versions?

Preview releases include features under active development and are recommended for development and testing only. Stable releases undergo rigorous testing for a longer period of time and are ready for production use.

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Release versioning
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### What are the upcoming features?

The roadmap for upcoming releases and the list of recently released features can be found in the [yugabyte-db](https://github.com/yugabyte/yugabyte-db) repository on GitHub.

{{<lead link="https://github.com/yugabyte/yugabyte-db?tab=readme-ov-file#current-roadmap">}}Current roadmap{{</lead>}}

### Which companies are currently using YugabyteDB in production?

Global organizations of all sizes leverage YugabyteDB to fulfill their application requirements.

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Success stories
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### How do I report a security vulnerability?

Follow the steps in the [vulnerability disclosure policy](../../secure/vulnerability-disclosure-policy) to report a vulnerability to our security team. The policy outlines our commitments to you when you disclose a potential vulnerability, the reporting process, and how we will respond.

### What are YugabyteDB Anywhere and YugabyteDB Aeon?

| Product | Description |
| :--- | :--- |
| [YugabyteDB](../../) | The 100% open source core database. It is the best choice for startup organizations with strong technical operations expertise looking to deploy to production with traditional DevOps tools. |
| [YugabyteDB Anywhere](../../yugabyte-platform/) | Commercial software for running a self-managed YugabyteDB-as-a-Service. It has built-in cloud native operations, enterprise-grade deployment options, and world-class support. |
| [YugabyteDB Aeon](../../yugabyte-cloud/) | Fully-managed cloud service on Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP). [Sign up](https://cloud.yugabyte.com/) to get started. |

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Compare deployment options
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### When is YugabyteDB a good fit?

YugabyteDB is a good fit for fast-growing, cloud-native applications that need to serve business-critical data reliably, with zero data loss, high availability, and low latency. Common use cases include:

- Distributed Online Transaction Processing (OLTP) applications needing multi-region scalability without compromising strong consistency and low latency. For example, user identity, Retail product catalog, Financial data service.

- Hybrid Transactional/Analytical Processing (HTAP) (also known as Translytical) applications needing real-time analytics on transactional data. For example, user personalization, fraud detection, machine learning.

- Streaming applications needing to efficiently ingest, analyze, and store ever-growing data. For example, IoT sensor analytics, time series metrics, real-time monitoring.

### When is YugabyteDB not a good fit?

YugabyteDB is not a good fit for traditional Online Analytical Processing (OLAP) use cases that need complete ad-hoc analytics. Use an OLAP store such as [Druid](http://druid.io/druid.html) or a data warehouse such as [Snowflake](https://www.snowflake.net/).

### What are the trade-offs of using YugabyteDB?

Ensuring [ACID](../../architecture/key-concepts/#acid) transactions and full compatibility with the PostgreSQL API presents challenges in a distributed environment. The trade-offs can also vary depending on the database you're comparing it to. Here are a few key considerations when switching to YugabyteDB:

- **Consistency vs. Latency**: YugabyteDB uses the [Raft](../../architecture/docdb-replication/raft) consensus algorithm for strong consistency in distributed systems. While this guarantees data integrity, it can result in higher write latency compared to eventually consistent databases like Cassandra.

- **Data Distribution vs Query Latency**: Transactions and JOINs that span multiple nodes experience inter-node latency, making queries slower than in single-node databases like PostgreSQL.

  {{<note>}}
  [Many projects](https://github.com/yugabyte/yugabyte-db?tab=readme-ov-file#current-roadmap) are currently in progress to match the performance of a single-node database.
  {{</note>}}

- **Multi-Region vs Latency**: In multi-region or globally distributed setups, YugabyteDB replicates data across regions to ensure availability and resilience. However, this can lead to higher write latency due to cross-region coordination.

- **Availability vs Resource Requirements**: Being a distributed database, YugabyteDB demands more hardware and networking resources to maintain high availability and fault tolerance compared to traditional monolithic databases that run on a single machine.

- **Robustness vs PostgreSQL compatibility**: Every new PostgreSQL feature must be optimized and rigorously tested for distributed environments before being considered to be supported by YugabyteDB, which is not a simple task. Be sure to verify that the PostgreSQL features your application relies on are supported in the current version of YugabyteDB.

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PostgreSQL compatibility
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### What is a YugabyteDB universe?

A YugabyteDB [universe](/stable/architecture/key-concepts/#universe) comprises one [primary cluster](/stable/architecture/key-concepts/#primary-cluster) and zero or more [read replica clusters](/stable/architecture/key-concepts/#read-replica-cluster) that collectively function as a resilient and scalable distributed database. It is common to have just a primary cluster and hence the terms cluster and universe are sometimes used interchangeably but it is worthwhile to note that they are different.

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More key concepts
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### Are there any performance benchmarks available?

YugabyteDB is regularly benchmarked using a variety of standard benchmarks like [TPC-C](/stable/benchmark/tpcc/), [YCSB](/stable/benchmark/ycsb-ysql/), and [sysbench](/stable/benchmark/sysbench-ysql/).

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Benchmark
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### How is YugabyteDB tested for correctness?

Apart from the rigorous failure testing, YugabyteDB passes most of the scenarios in [Jepsen](https://jepsen.io/) testing. Jepsen is a methodology and toolset used to verify the correctness of distributed systems, particularly in the context of consistency models and fault tolerance and has become a standard for stress-testing distributed databases, data stores, and other distributed systems.

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Jepsen testing
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### How is YugabyteDB different from NoSQL databases?

YugabyteDB is a distributed SQL database with strong transactional capabilities, SQL support, and consistency, bridging the gap between traditional SQL databases and NoSQL systems. NoSQL databases, on the other hand, tend to favor horizontal scalability, flexibility in data models, and eventual consistency, often at the expense of full ACID transactions and complex querying.

- **Strong consistency**: YugabyteDB offers strong consistency, which is not always guaranteed in NoSQL systems that often prioritize availability over consistency and are typically designed for eventual consistency.

- **ACID transactions**: YugabyteDB supports ACID (Atomicity, Consistency, Isolation, Durability) transactions, including those spanning multiple nodes. Many NoSQL databases don't offer this level of transactional support.

- **Data Models**: YugabyteDB supports both relational (SQL) and semi-structured (JSON) data models, whereas most NoSQL databases are typically optimized for specific data models (such as document, key-value, wide-column).

### How does YugabyteDB compare to other databases?

We have published detailed comparison information against multiple SQL and NoSQL databases:

- **SQL** - [CockroachDB](../comparisons/cockroachdb/), [TiDB](../comparisons/tidb/), [Vitess](../comparisons/vitess/), [Amazon Aurora](../comparisons/amazon-aurora/), [Google Spanner](../comparisons/google-spanner/)
- **NOSQL** - [MongoDB](../comparisons/mongodb/), [FoundationDB](../comparisons/foundationdb/), [Cassandra](../comparisons/cassandra/), [DynamoDB](../comparisons/amazon-dynamodb/), [CosmosDB](../comparisons/azure-cosmos/)

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Compare YugabyteDB to other databases
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## PostgreSQL support

### How compatible is YugabyteDB with PostgreSQL?

YugabyteDB is [wire-protocol, syntax, feature, and runtime](https://www.yugabyte.com/postgresql/postgresql-compatibility/) compatible with PostgreSQL. But that said, supporting all PostgreSQL features in a distributed system is not always feasible.

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PostgreSQL compatibility
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### Can I use my existing PostgreSQL tools and drivers with YugabyteDB?

Yes. YugabyteDB is [fully compatible](#how-compatible-is-yugabytedb-with-postgresql) with PostgreSQL and automatically works well with most of PostgreSQL tools.

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Integrations
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### Are PostgreSQL extensions supported?

YugabyteDB pre-bundles many popular extensions and these should be readily available on your cluster. But given the distributed nature of YugabyteDB, not all extensions are supported by default.

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PostgreSQL extensions
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### How can I migrate from PostgreSQL?

YugabyteDB is fully compatible with PostgreSQL and so most PostgreSQL applications should work as is. To address corner cases, we have published a [comprehensive guide](/stable/manage/data-migration/migrate-from-postgres/) to help you migrate from PostgreSQL.

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Migrate data
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## Architecture

### How does YugabyteDB distribute data?

The table data is split into [tablets](/stable/architecture/key-concepts/#tablet) and the table rows are mapped to the tablets via [sharding](/stable/explore/linear-scalability/data-distribution/). The tablets themselves are distributed across the various nodes in the cluster.

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Data distribution
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### How does YugabyteDB scale?

YugabyteDB scales seamlessly when new nodes are added to the cluster without any service disruption. Table data is [stored distributed](#how-does-yugabytedb-distribute-data) in tablets. When new nodes are added, the rebalancer moves certain tablets to other nodes and keeps the number of tablets on each node more or less the same. As data grows, these tablets also split into two and are moved to other nodes.

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Horizontal scalability
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### How does YugabyteDB provide high availability?

YugabyteDB replicates [tablet](/stable/architecture/key-concepts/#tablet) data onto [followers](/stable/architecture/key-concepts/#tablet-follower) of the tablet via [RAFT](/stable/architecture/docdb-replication/raft/) consensus. This ensures that a consistent copy of the data is available in case of failures. On failures, one of the tablet followers is promoted to be the [leader](/stable/architecture/key-concepts/#tablet-leader).

{{<lead link="/stable/explore/fault-tolerance/">}}
Resiliency and high availability
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### How is data consistency maintained across multiple nodes?

Every write (insert, update, delete) to the data is replicated via [RAFT](/stable/architecture/docdb-replication/raft/) consensus to [tablet followers](/stable/architecture/key-concepts/#tablet-follower) as per the [replication factor (RF)](/stable/architecture/key-concepts/#replication-factor-rf) of the cluster. Before acknowledging the write operation back to the client, YugabyteDB ensures that the data is replicated to a quorum (RF/2 + 1) of followers.

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Synchronous replication
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### What is tablet splitting?

Data is stored in [tablets](/stable/architecture/key-concepts/#tablet). As the tablet grows, the tablet splits into two. This enables some data to be moved to other nodes in the cluster.

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Tablet splitting
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### Are indexes colocated with tables?

Indexes are not typically colocated with the base table. The sharding of indexes is based on the primary key of the index and is independent of how the main table is sharded/distributed which is based on the primary key of the table.

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Explore indexes
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Colocating tables
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### How can YugabyteDB be both CP and ensure high availability at the same time?

In terms of the [CAP theorem](https://www.yugabyte.com/blog/a-for-apple-b-for-ball-c-for-cap-theorem-8e9b78600e6d), YugabyteDB is a consistent and partition-tolerant (CP) database. It ensures high availability (HA) for most practical situations even while remaining strongly consistent. While this may seem to be a violation of the CAP theorem, that is not the case. CAP treats availability as a binary option whereas YugabyteDB treats availability as a percentage that can be tuned to achieve high write availability (reads are always available as long as a single node is available).

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Partition Tolerance - CAP
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