## Context
Our Flexible Schema engine dynamically generates entities/tables/APIs
for us but was not flexible enough to build indexes in the DB. With more
and more features involving heavy queries such as Messaging, we are now
adding a new WorkspaceIndex() decorator for our standard objects (will
come later for custom objects). This decorator will give enough
information to the workspace sync metadata manager to generate the
proper migrations that will create or drop indexes on demand.
To be aligned with the rest of the engine, we are adding 2 new tables:
IndexMetadata and IndexFieldMetadata, that will store the info of our
indexes.
## Implementation
```typescript
@WorkspaceEntity({
standardId: STANDARD_OBJECT_IDS.person,
namePlural: 'people',
labelSingular: 'Person',
labelPlural: 'People',
description: 'A person',
icon: 'IconUser',
})
export class PersonWorkspaceEntity extends BaseWorkspaceEntity {
@WorkspaceField({
standardId: PERSON_STANDARD_FIELD_IDS.email,
type: FieldMetadataType.EMAIL,
label: 'Email',
description: 'Contact’s Email',
icon: 'IconMail',
})
@WorkspaceIndex()
email: string;
```
By simply adding the WorkspaceIndex decorator, sync-metadata command
will create a new index for that column.
We can also add composite indexes, note that the order is important for
PSQL.
```typescript
@WorkspaceEntity({
standardId: STANDARD_OBJECT_IDS.person,
namePlural: 'people',
labelSingular: 'Person',
labelPlural: 'People',
description: 'A person',
icon: 'IconUser',
})
@WorkspaceIndex(['phone', 'email'])
export class PersonWorkspaceEntity extends BaseWorkspaceEntity {
```
Currently composite fields and relation fields are not handled by
@WorkspaceIndex() and you will need to use this notation instead
```typescript
@WorkspaceIndex(['companyId', 'nameFirstName'])
export class PersonWorkspaceEntity extends BaseWorkspaceEntity {
```
<img width="700" alt="Screenshot 2024-06-21 at 15 15 45"
src="https://github.com/twentyhq/twenty/assets/1834158/ac6da1d9-d315-40a4-9ba6-6ab9ae4709d4">
Next step: We might need to implement more complex index expressions,
this is why we have an expression column in IndexMetadata.
What I had in mind for the decorator, still open to discussion
```typescript
@WorkspaceIndex(['nameFirstName', 'nameLastName'], { expression: "$1 || ' ' || $2"})
export class PersonWorkspaceEntity extends BaseWorkspaceEntity {
```
---------
Co-authored-by: Charles Bochet <charles@twenty.com>
e13dc7a1fc