Evolving Schemas in Production

Your graph schema will change as your application grows. This guide covers how to make those changes safely — from adding a field to renaming a node type.

For API reference, see Schema Migrations.

How Schema Evolution Works

When you call createStoreWithSchema(), TypeGraph:

1. Serializes your current graph definition
2. Compares it against the stored schema (by hash, then by diff)
3. Safe changes — auto-migrates and bumps the version
4. Breaking changes — throws MigrationError (or returns status: "breaking")

The key insight: TypeGraph manages schema metadata, not data migration. When you add an optional field, TypeGraph records that the schema now includes it. It does not alter existing rows — Zod defaults handle that at read time.

Safe Changes

These changes are backwards compatible and auto-migrate without intervention:

• Adding new node types
• Adding new edge types
• Adding optional properties (with defaults)
• Adding ontology relations

Adding an Optional Property

// Version 1
const Person = defineNode("Person", {
  schema: z.object({
    name: z.string(),
  }),
});

// Version 2 — safe, auto-migrates
const Person = defineNode("Person", {
  schema: z.object({
    name: z.string(),
    email: z.string().optional(),
  }),
});

On startup, createStoreWithSchema() returns status: "migrated". Existing Person nodes return email: undefined — no data transformation needed.

Adding a Node Type with Edges

// Version 2 — add Company and worksAt in one deploy
const Company = defineNode("Company", {
  schema: z.object({ name: z.string() }),
});

const worksAt = defineEdge("worksAt", {
  schema: z.object({ role: z.string() }),
});

const graph = defineGraph({
  id: "my_app",
  nodes: {
    Person: { type: Person },
    Company: { type: Company },
  },
  edges: {
    worksAt: { type: worksAt, from: [Person], to: [Company] },
  },
});

This is a single safe migration. New node and edge types don’t affect existing data.

Breaking Changes

These require explicit handling:

• Removing node or edge types
• Removing properties
• Adding required properties (no default)
• Renaming types or properties

TypeGraph will throw MigrationError by default. You have two options: fix the schema to be backwards compatible, or use the expand-contract pattern.

The Expand-Contract Pattern

For breaking changes, use a multi-deploy strategy. This is the same pattern used in relational database migrations — deploy in phases so there’s never a moment where running code is incompatible with the schema.

Renaming a Property

Rename name to fullName on Person in three deploys:

Deploy 1 — Expand: add the new property

const Person = defineNode("Person", {
  schema: z.object({
    name: z.string(),
    fullName: z.string().optional(), // New property, optional for now
  }),
});

Safe migration. Then backfill existing data:

const [store] = await createStoreWithSchema(graph, backend);

const people = await store.query(Person).execute();
for (const person of people) {
  if (!person.properties.fullName) {
    await store.nodes.Person.update(person.id, {
      fullName: person.properties.name,
    });
  }
}

Deploy 2 — Switch: use the new property everywhere

Update all application code to read/write fullName instead of name. Both properties still exist, so this deploy is safe.

Deploy 3 — Contract: remove the old property

const Person = defineNode("Person", {
  schema: z.object({
    fullName: z.string(),
  }),
});

This is a breaking change (removing name). Use migrateSchema() to force it:

import { getSchemaChanges, migrateSchema } from "@nicia-ai/typegraph/schema";

const [store, result] = await createStoreWithSchema(graph, backend, {
  throwOnBreaking: false,
});

if (result.status === "breaking") {
  // We've already backfilled — safe to force migrate
  const activeSchema = await backend.getActiveSchema(graph.id);
  await migrateSchema(backend, graph, activeSchema!.version);
}

Removing a Node Type

Deploy 1 — Stop creating new instances

Update application code to stop creating the deprecated node type. Existing data remains.

Deploy 2 — Clean up references

Delete edges that reference the deprecated node type, then delete the nodes themselves:

// Delete all edges connected to deprecated nodes
const deprecated = await store.query(OldNode).execute();
for (const node of deprecated) {
  await store.nodes.OldNode.delete(node.id);
}

Deploy 3 — Remove from schema

Remove the node type from defineGraph() and force migrate.

Changing a Property Type

Change age from z.string() to z.number():

Deploy 1 — Add the new property

const Person = defineNode("Person", {
  schema: z.object({
    age: z.string(),
    ageNumeric: z.number().optional(),
  }),
});

Deploy 2 — Backfill and switch

const people = await store.query(Person).execute();
for (const person of people) {
  if (person.properties.ageNumeric === undefined) {
    await store.nodes.Person.update(person.id, {
      ageNumeric: parseInt(person.properties.age, 10),
    });
  }
}

Deploy 3 — Contract

Remove age, rename ageNumeric to age with the new type, and force migrate.

Pre-Deploy Schema Checks

Use getSchemaChanges() in CI to catch breaking changes before they reach production.

CI/CD Script

import { getSchemaChanges } from "@nicia-ai/typegraph/schema";

async function checkSchema(backend: GraphBackend, graph: GraphDef) {
  const diff = await getSchemaChanges(backend, graph);

  if (!diff) {
    console.log("No existing schema — first deploy");
    return;
  }

  if (!diff.hasChanges) {
    console.log("Schema unchanged");
    return;
  }

  console.log("Schema changes detected:");
  console.log(diff.summary);

  for (const change of [...diff.nodes, ...diff.edges]) {
    const icon =
      change.severity === "safe"
        ? "[safe]"
        : change.severity === "warning"
          ? "[warn]"
          : "[BREAKING]";
    console.log(`  ${icon} ${change.details}`);
  }

  if (diff.hasBreakingChanges) {
    console.error("Breaking changes require migration before deploy.");
    process.exit(1);
  }
}

Staging Validation

Before deploying to production, run against a staging database that mirrors production schema state:

const [store, result] = await createStoreWithSchema(graph, stagingBackend);

switch (result.status) {
  case "initialized":
    console.log("Staging DB was empty — initialized");
    break;
  case "migrated":
    console.log(
      `Auto-migrated v${result.fromVersion} → v${result.toVersion}`,
    );
    console.log("Changes:", result.diff.summary);
    break;
  case "breaking":
    console.error("Would break in production. Fix before deploying.");
    process.exit(1);
    break;
}

Testing Schema Changes

Unit Testing Migrations

Test that your migration code handles existing data correctly:

import { createStoreWithSchema, defineGraph, defineNode } from "@nicia-ai/typegraph";
import { createTestBackend } from "./test-utils";

it("migrates name to fullName", async () => {
  const backend = createTestBackend();

  // Set up v1 with data
  const graphV1 = defineGraph({
    id: "test",
    nodes: { Person: { type: PersonV1 } },
    edges: {},
  });
  const [storeV1] = await createStoreWithSchema(graphV1, backend);
  await storeV1.nodes.Person.create({ name: "Alice" });

  // Migrate to v2 (expand phase)
  const graphV2 = defineGraph({
    id: "test",
    nodes: { Person: { type: PersonV2WithBothFields } },
    edges: {},
  });
  const [storeV2, result] = await createStoreWithSchema(graphV2, backend);
  expect(result.status).toBe("migrated");

  // Run backfill
  const people = await storeV2.query(PersonV2WithBothFields).execute();
  for (const person of people) {
    await storeV2.nodes.Person.update(person.id, {
      fullName: person.properties.name,
    });
  }

  // Verify
  const updated = await storeV2.query(PersonV2WithBothFields).execute();
  expect(updated[0].properties.fullName).toBe("Alice");
});

Previewing Changes Without Applying

Use getSchemaChanges() to see what would change without modifying the database:

import { getSchemaChanges } from "@nicia-ai/typegraph/schema";

const diff = await getSchemaChanges(backend, newGraph);
if (diff?.hasChanges) {
  console.log("Pending changes:", diff.summary);
  console.log("Breaking:", diff.hasBreakingChanges);

  for (const change of diff.nodes) {
    console.log(`  ${change.severity}: ${change.details}`);
  }
}

Version History

TypeGraph preserves all schema versions in the typegraph_schema_versions table. Only one version is active at a time.

typegraph_schema_versions
├── version 1 (initial)           ← inactive
├── version 2 (added email)       ← inactive
├── version 3 (added Company)     ← active

Access version history through the backend:

// Get a specific version
const v1 = await backend.getSchemaVersion("my_app", 1);
console.log("V1 created at:", v1?.created_at);

// Get the active version
const active = await backend.getActiveSchema("my_app");
console.log("Current version:", active?.version);

Summary: Change Classification

Change	Classification	Auto-Migrated?
Add node type	Safe	Yes
Add edge type	Safe	Yes
Add optional property	Safe	Yes
Add ontology relation	Safe	Yes
Add required property	Breaking	No
Remove property	Breaking	No
Remove node/edge type	Breaking	No
Rename node/edge type	Breaking	No
Change property type	Breaking	No
Change onDelete behavior	Warning	Yes
Change unique constraints	Warning	Yes
Change edge cardinality	Warning	Yes
Change edge endpoint kinds	Warning	Yes

Rollback

If a deployment goes wrong, you can switch back to a previous schema version. Version history is always preserved — rollbackSchema() simply changes which version is active.

import { rollbackSchema } from "@nicia-ai/typegraph/schema";

// Roll back to version 2
await rollbackSchema(backend, "my_app", 2);

This does not delete newer versions. You can migrate forward again later.

Migration Hooks

Use onBeforeMigrate and onAfterMigrate for observability — logging, metrics, and alerts during schema migrations:

const [store, result] = await createStoreWithSchema(graph, backend, {
  onBeforeMigrate: (context) => {
    console.log(`Migrating ${context.graphId} v${context.fromVersion} → v${context.toVersion}`);
    console.log("Changes:", context.diff.summary);
  },
  onAfterMigrate: (context) => {
    console.log(`Migration complete: v${context.toVersion}`);
    metrics.increment("schema_migrations_total");
  },
});

For data transformations (backfill scripts), run them explicitly after store creation rather than inside hooks. This gives you control over retries and error handling:

const [store, result] = await createStoreWithSchema(graph, backend);

if (result.status === "migrated" && result.toVersion === 3) {
  // Backfill fullName from name for the expand phase
  const people = await store.query(Person).execute();
  for (const person of people) {
    if (!person.properties.fullName) {
      await store.nodes.Person.update(person.id, {
        fullName: person.properties.name,
      });
    }
  }
}

Current Limitations

• No automatic data transformation. TypeGraph tracks schema metadata changes but does not transform existing rows. Use backfill scripts (or onAfterMigrate hooks) for data migration.
• No rename detection. Renaming a property looks like a removal + addition. Use the expand-contract pattern instead.
• Schema-level only. Migrations operate on the graph definition, not on underlying database tables. TypeGraph’s storage tables are schema-agnostic (nodes and edges are stored as JSON properties), so “schema migration” means updating the metadata that TypeGraph tracks, not running ALTER TABLE.