# ER Model

> How Pigsty abstracts different functionality into modules, and the E-R diagrams for these modules.

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LLMS index: [llms.txt](/llms.txt)

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The largest entity concept in Pigsty is a **Deployment**. The main entities and relationships (E-R diagram) in a deployment are shown below:

![Pigsty full data model ER diagram](/img/pigsty/er-full.svg)

A deployment can also be understood as an **Environment**. For example, Production (Prod), User Acceptance Testing (UAT), Staging, Testing, Development (Devbox), etc.
Each environment corresponds to a Pigsty [**inventory**](/docs/concept/iac/inventory) that describes all entities and attributes in that environment.

Typically, an environment includes shared infrastructure ([**`INFRA`**](/docs/infra)), which broadly includes [**`ETCD`**](/docs/etcd) (HA DCS) and [**`MINIO`**](/docs/minio) (centralized backup repository),
serving multiple PostgreSQL database clusters (and other database module components). (Exception: there are also [**deployments without infrastructure**](/docs/setup/slim))

In Pigsty, almost all database modules are organized as "**Clusters**". Each cluster is an Ansible group containing several node resources.
For example, PostgreSQL HA database clusters, Redis, Etcd, and Silo all exist as clusters. An environment can contain multiple clusters.

- [**PostgreSQL Cluster**](/docs/concept/model/pgsql)
- [**ETCD Cluster**](/docs/concept/model/etcd)
- [**MinIO Cluster**](/docs/concept/model/minio)
- [**Redis Cluster**](/docs/concept/model/redis)
- [**INFRA Nodes**](/docs/concept/model/infra)

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Section pages:

- [E-R Model of Infra Cluster](/docs/concept/model/infra/): Entity-Relationship model for INFRA infrastructure nodes in Pigsty, component composition, and naming conventions.
- [E-R Model of PostgreSQL Cluster](/docs/concept/model/pgsql/): Entity-Relationship model for PostgreSQL clusters in Pigsty, including E-R diagram, entity definitions, and naming conventions.
- [E-R Model of Etcd Cluster](/docs/concept/model/etcd/): Entity-Relationship model for ETCD clusters in Pigsty, including E-R diagram, entity definitions, and naming conventions.
- [MINIO Cluster Model](/docs/concept/model/minio/): The cluster, instance, and node identity model used when Pigsty's MINIO module deploys Silo.
- [E-R Model of Redis Cluster](/docs/concept/model/redis/): Entity-Relationship model for Redis clusters in Pigsty, including E-R diagram, entity definitions, and naming conventions.