| name | snapshot-projection |
| description | Creates @materialize.snapshot aggregation projections in SAP CAP. Use when defining group by snapshots, sum/count aggregates, schedule options, or the materialized aspect on target entities. |
Snapshot projection
Minimal pattern
using from 'cds-data-pipeline/db';
namespace reporting;
@materialize.snapshot: {
schedule : '0 2 * * *',
source : { service: 'db' }
}
entity DailyCustomerRevenue as projection on sales.Orders {
key customerId,
sum(amount) as totalAmount : Decimal(15, 2),
count(*) as orderCount : Integer,
max(modifiedAt) as lastActivity : Timestamp
}
group by customerId;
source.service is the cds.requires key that executes the aggregate (typically db for local tables).
Annotation options
| Option | Description |
|---|
schedule | Cron or interval for pipeline runs |
refresh | Default full — rebuild entire snapshot each run |
name | Pipeline tracker name (default: entity name) |
source.service | Required when from ref is not Service.Entity |
Optional materialized aspect
using { plugin.data_materialization as materialization } from 'cds-data-materialization';
entity DailyCustomerRevenue : materialization.materialized {
key customerId : String(10);
totalAmount : Decimal(15, 2);
}
Adds lastMaterializedAt and lastMaterializedBy.
Compiler rules (v1)
Supported:
- Single-entity
projection on
- Standard aggregates with
as aliases
group by on projected keys- Optional static
where on the projection
Rejected at scan time:
- Path expressions in SELECT
- Expand/join columns
- Cross-source joins in one materialization
@federation.* on the same entity
Stage-then-aggregate pattern
Remote OData cannot be the aggregate source. Workflow:
@federation.replicate remote entity into local table@materialize.snapshot on group by over the local table with source.service: 'db'
Anti-patterns
❌ Wrong:
@materialize.snapshot: { source: { service: 'RemoteOData' } }
entity DailyRevenue as projection on remote.Orders { ... }
group by customerId;
✅ Correct — replicate first, aggregate from db.
❌ Wrong — @materialize.snapshot: { refresh: 'partial' } in annotation.
✅ Correct — full refresh in v1; use engine API for partial refresh with refresh.slice.
Docs
