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Modifying Schema

Tigris provides a lightweight way to modify the schema. Within Tigris, the schema change is a metadata operation and hence doesn't require rebuilding the entire collection. The updated schema is made available immediately to new write operations.

However, there are certain restrictions on the type of modifications allowed. These restrictions are in place to ensure that we don't need to rebuild collections on schema changes.

Allowed modifications​

The following schema changes are currently supported:

  • Adding a new field to an existing collection
  • Defining a maximum length constraint on existing string or byte type fields. The constraint will only apply to documents added after the constraint is defined
  • Increasing the maximum length constraint on existing string or byte type fields.

Unsupported modifications​

The following schema changes are currently not supported:

  • Changing the data type of a field
  • Removing a field from the schema
  • Adding or removing a field from the primary key definition

How to modify the schema​

Suppose you have the following data model defined:

./db/models/catalog.ts
export class ProductAttributes {
  name!: string;
  value!: string;
}

@TigrisCollection("catalog")
export class Catalog {
  @PrimaryKey(TigrisDataTypes.INT64, { order: 1, autoGenerate: true })
  id!: bigint;

  @Field()
  name!: string;

  @Field()
  price!: number;

  @Field({ elements: ProductAttributes })
  attributes!: Array<ProductAttributes>;
}

And you would like to modify the model and add a new field brand of type string. The steps to make this change are as follows:

1. Update the data model in your application code​

// ./db/models/catalog.ts

export class ProductAttributes {
  name!: string;
  value!: string;
}

@TigrisCollection("catalog")
export class Catalog {
  @PrimaryKey(TigrisDataTypes.INT64, { order: 1, autoGenerate: true })
  id!: bigint;

  @Field()
  name!: string;

  @Field()
  price!: number;

  @Field({ elements: ProductAttributes })
  attributes!: Array<ProductAttributes>;
+
+  @Field()
+  brand!: string;
}

2. Use the createOrUpdateCollection API in your application code​

Just as you use the createOrUpdateCollection API in your application code to create the collection. The same API will update the schema of the collection to reflect the new schema.

await db.createOrUpdateCollection<Catalog>(Catalog);

At this point, the collection's schema is modified. The collection is instantaneously available with the new schema and any write requests after this point will be validated with the new schema.