> ## Documentation Index
> Fetch the complete documentation index at: https://thenile.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Architecture of Nile Postgres

Nile has built Postgres from the ground up with tenants/customers as a core building block. The key highlights of our design are:

**Decoupled storage and compute**. The compute layer is essentially Postgres, modified to store each tenant's data in separate pages. The storage layer consists of a fleet of machines that house these pages. An external machine stores the log, while both the log and pages are archived in S3 for long-term storage.

**Tenant-aware Postgres pages**. A typical Postgres database comprises objects like tables and indexes, represented by 8KB pages. In Nile, tables are either tenant-specific or shared. Each page of a tenant table belongs exclusively to one tenant, with all records within a page associated with that tenant. This decoupled storage and tenant-dedicated page system allows for instantaneous tenant migration between different Postgres compute instances. Moving a tenant simply involves transferring tenant leadership from one compute instance to another while maintaining references to the same pages in the storage layer.

<img src="https://mintcdn.com/nile/SZ6JYQiPYP1_QgSP/images/nile-arch.png?fit=max&auto=format&n=SZ6JYQiPYP1_QgSP&q=85&s=bd1f352259fcfe58fda6374dbbc9c261" alt="nilearchitecture" width="8199" height="4992" data-path="images/nile-arch.png" />

**Support for both serverless and provisioned compute.** The Postgres compute layer offers two types of compute. Serverless compute is built with true multitenancy, while provisioned compute is dedicated to a single Nile customer. Nile users can have any number of provisioned compute instances in the same database. Tenants can be placed on either serverless or provisioned compute.

**Distributed querying across tenants and a central schema store.** The distributed query layer operates across tenants and functions between serverless and provisioned compute instances. A central schema store employs distributed transactions to apply schemas to every tenant during DDL execution. This ensures correct schema application and enables schema recovery for tenants during failures.

**A global gateway for tenant routing, inter-region communication, and connection pooling.** The gateway uses the Postgres protocol to route requests to different tenants. It can communicate with gateways in other regions and serves as a connection pooling layer, eliminating the need for a separate pooler.