# Schemas

Choose a schema source, combine or validate it, and turn the result into documentation, diagrams, or API contracts.

Source: https://docs.ptah.run/v0.8.1/schema/overview/

import { LinkCard, CardGrid } from '@astrojs/starlight/components';

Ptah reads SQL, YAML, HCL, DBML, Go annotations, ORM loaders, and live databases
into one schema model. Choose the format your project already owns; the
validation, comparison, rendering, and export stages use the same model after
the source is read.

## Common tasks

<CardGrid>
  <LinkCard title="Choose a schema source" href="../work-with-a-source/" description="Compare the formats and decide which artifact remains authoritative." />
  <LinkCard title="Validate and format" href="../validate-and-format/" description="Refuse invalid input and produce a stable formatted representation." />
  <LinkCard title="Visualize the schema" href="../visualize/" description="Render table and relationship structure as Mermaid, DOT, SVG, or an image." />
  <LinkCard title="Generate documentation" href="../document/" description="Create Markdown or a self-contained HTML reference from the schema." />
  <LinkCard title="Export an API contract" href="../export/" description="Produce OpenAPI, GraphQL, or Protobuf output from the same schema model." />
</CardGrid>

## Decide what owns the schema

Use one source when possible. Use a [composite desired schema](../composite/)
only when separate sources own separate parts of the database and their object
names do not conflict.

A schema source describes what should exist. It does not decide whether the
difference reaches the database as [versioned migrations](../../versioned/overview/)
or a [direct schema change](../../direct/overview/).

## Reference

Use the format references for exact accepted fields and directives:
[Go annotations](../../reference/go-annotations/),
[HCL](../../reference/hcl-schema/), and
[YAML](../../reference/yaml-schema/).