# Create Indexes Example

> Example showing how to create indexes on any database from custom code with g.sys.system.createIndexes, safe to run again and again.

Source: https://docs.apimaker.dev/v1/examples/sys/system/createIndexes.html

`g.sys.system.createIndexes` calls the [create indexes system API](https://docs.apimaker.dev/v1/docs/apis-all/system-apis/system-generated-create-indexes-api.html) from your code, whatever the settings of that API say about HTTP callers.

### Create indexes System API

Create indexes using global object 'g'. The same request works on MongoDB, MySQL, MariaDB, SQL Server, PostgreSQL and Oracle ; an index which exists already is left alone (`EXISTS`), a field the database can not index is `SKIPPED` with the reason, a refusal of the database is `FAILED` with its message.

```ts
const results = await g.sys.system.createIndexes({
    indexes: [
        {
            instance: 'mysql8',
            database: 'inventory',
            table: 'orders',
            fields: [{ name: 'customer_id' }, { name: 'status', order: 'DESC' }],
        },
        {
            instance: 'mongodb',
            database: 'inventory',
            collection: 'products',
            name: 'ux_products_sku',
            unique: true,
            fields: [{ name: 'sku' }],
        },
    ],
    ifNotExists: true,      // default : nothing is created twice
    continueOnError: true,  // default : one refused index does not stop the others
    skipUnindexable: true,  // default : TEXT, json, CLOB... are skipped before the database is asked
});
// results[0] : { status: 'CREATED', name: 'am_ix_orders_customer_id_status_3f9a1c', fields: ['customer_id', 'status'], ... }
// results[1] : { status: 'EXISTS', message: 'The index "ux_products_sku" exists already.', ... }
```

- Without a `name`, the index is called `am_ix_<table>_<fields>_<hash>` (`am_ixu_` when unique), the same in every environment, cut to the limit of the database (30 characters on Oracle).
- `order` : `ASC`, `DESC`, `HASHED` and `TEXT` (MongoDB) ; `nullsFirst: true` on PostgreSQL. `type` : `FULLTEXT` or `SPATIAL` (MySQL), `CLUSTERED`, `XML`, `SPATIAL` (SQL Server), `hash`, `gin`, `gist`, `spgist`, `brin` (PostgreSQL). `method` : `BTREE`, `HASH`, `RTREE` (MySQL).
- This is the call the migration script `am_index_maker` of [Index Maker](https://docs.apimaker.dev/v1/extensions/index_maker/automatic_indexes.html) makes on deploy : a migration script of your own can do the same.

### Multi-tenant
- `instance: "crm::acme"` creates the index in the database of the tenant `acme` of the [multi-tenant](https://docs.apimaker.dev/v1/docs/features/multi-tenant.html) instance `crm`. In a custom API called for a tenant, `instance: "crm"` creates it in the database of that tenant.

```ts
await g.sys.system.createIndexes({
    indexes: [{ instance: 'crm::acme', database: 'crm', collection: 'customers', fields: [{ name: 'email' }], unique: true }],
});
```

## Related

- [Create indexes system API](https://docs.apimaker.dev/v1/docs/apis-all/system-apis/system-generated-create-indexes-api.html) · [All system APIs from code](https://docs.apimaker.dev/v1/examples/sys/system/system.html) · [The global object g](https://docs.apimaker.dev/v1/docs/pre-defined-terms/global-object-g.html)