> For the complete documentation index, see [llms.txt](https://docs.carto.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.carto.com/carto-self-hosted/concepts/metadata-database-vs-data-warehouse.md).

# Metadata Database vs. Data Warehouse

## Overview

CARTO Self-Hosted involves two distinct database systems that are often confused. This page clarifies their roles.

## The metadata database (PostgreSQL)

The **metadata database** is a PostgreSQL instance that CARTO Self-Hosted uses internally to store platform state: maps, workflows, connections, users, and organization settings. You provision and manage this database as part of your CARTO infrastructure.

* **Managed by:** You (customer)
* **Technology:** PostgreSQL
* **Contains:** Platform metadata (not your spatial data)
* **Size:** Typically small — scales with the number of CARTO users and maps

## The data warehouse

The **data warehouse** is the external database where your **spatial data** lives. CARTO connects to it to run analyses, visualize data, and power maps. CARTO does not manage this database; it connects to it using credentials you provide.

* **Managed by:** You (customer) or your cloud provider
* **Technology:** BigQuery, Snowflake, Redshift, PostgreSQL, Databricks, etc.
* **Contains:** Your spatial datasets and analysis results
* **Size:** Scales with your data volume

## Side-by-side comparison

|                       | Metadata Database                 | Data Warehouse                        |
| --------------------- | --------------------------------- | ------------------------------------- |
| **Purpose**           | Store CARTO platform state        | Store and query your spatial data     |
| **Technology**        | PostgreSQL                        | BigQuery, Snowflake, Redshift, etc.   |
| **Managed by**        | Customer (as part of CARTO infra) | Customer (external system)            |
| **Required**          | Yes, always                       | Yes, at least one connection required |
| **CARTO accesses it** | Internally, always                | Via connections you configure         |
| **Size**              | Small (metadata only)             | Large (your data)                     |

## How they relate at runtime

```mermaid
flowchart LR
  subgraph "Your infrastructure"
    MD[("Metadata Database\nPostgreSQL")]
    DW[("Data Warehouse\nBigQuery / Snowflake / etc.")]
  end
  subgraph "CARTO Self-Hosted"
    SVC["CARTO Services"]
  end
  U["Users / API clients"] --> SVC
  SVC -->|"platform state\n(maps, users, config)"| MD
  SVC -->|"spatial data queries\n(tiles, analyses)"| DW
```

The metadata database is always accessed by CARTO internally. The data warehouse is accessed on behalf of users when they open maps, run workflows, or execute queries.

## Next steps

* [How CARTO uses the Metadata Database](/carto-self-hosted/concepts/metadata-database.md) — what is stored and why
* [Metadata Database prerequisites](/carto-self-hosted/planning/prerequisites/metadata-database.md) — supported versions, managed service options, and checklist
* [Plan Your Deployment](/carto-self-hosted/planning.md) — prerequisites, sizing, and deployment method selection


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