# Evolve your schema with confidence, backed by field-level data

See exactly which clients and operations use every field in your schema. Request counts, first and last seen timestamps, and subgraph visibility. Make deprecation decisions based on data, not guesswork.

## The problem

### Schema changes without usage data break things

Without field-level usage visibility, every schema change is a risk. Teams either move too slowly out of caution or too quickly and break clients.

### Schema changes break clients you did not know about

Without usage data, removing a field is a guess. The clients affected find out when their queries start failing, not before you make the change.

### Deprecation timelines have no factual basis

Teams pick deprecation sunset dates based on intuition or policy, not on how recently the field was last used. The result is either too aggressive (breaking active clients) or too conservative (keeping dead fields forever).

### Migration communication is untargeted

Without knowing which specific client teams use a deprecated field, breaking change announcements go to everyone. Teams ignore notifications that are not relevant to them.

## Our solution

### Complete visibility into every field access

Schema Field Usage aggregates field-level data from every request processed by the Cosmo Router. For any field in your schema, you can see which clients use it, how often, which operations include it, and when it was last seen — all with date filtering for trend analysis.

### What you get for each field

1. Schema Field Usage tracks every field access from requests processed by the Cosmo Router.
2. For each field, you see a breakdown of every client that uses it, which operations include it, and how many requests touch it.
3. First seen and last seen timestamps show when the field was first accessed and when it was most recently used.
4. Subgraph contribution visibility shows which subgraphs serve each field.
5. Date and time filtering lets you narrow the usage view to any period to analyze trends.
6. The data is accessible from both the schema explorer and schema check pages.
7. Available for all GraphQL types.

## Before & After

| Before Cosmo | With Cosmo |
| --- | --- |
| Guessing which fields are safe to deprecate | Data-driven deprecation decisions |
| No visibility into client-specific field usage | Per-client breakdown of field consumption |
| Unknown impact of schema changes | Clear view of which operations use each field |
| Manual tracking of field lifecycle | Automatic first seen and last seen timestamps |

### What each field shows

- **Clients and operations**: Every client using the field, with the operations they send and request counts.
- **First seen / last seen**: Timestamps for the earliest and most recent access within the selected date range.
- **Contributing subgraphs**: Which subgraphs serve the field — useful for migration planning.
- **Date filtering**: Narrow usage data to any date range to analyze trends or check recent activity.

## How Schema Field Usage works

01

### Find the field

Navigate to Schema Field Usage from the schema explorer or schema check page. Search for the field you want to analyze.

02

### Review client usage

See every client that uses the field along with the operations they send and the number of requests made. This data drives targeted deprecation communication.

03

### Check lifecycle dates

First seen tells you when the field was first accessed in the selected period. Last seen tells you when it was most recently used. These timestamps make sunset decisions factual.

04

### Identify contributing subgraphs

See which subgraphs serve the field. Useful when planning migrations that involve moving a field between subgraphs or changing the resolving service.

## What is included

### Available on Pro and Enterprise

Schema Field Usage requires a Pro or Enterprise plan.

### Safe schema evolution

Know exactly which fields are used before deprecating or removing them. Replace guesswork with a clear, per-client usage breakdown.

### Client-aware decisions

See which specific clients use each field. Target deprecation communication at the teams that are actually affected, not everyone.

### Lifecycle insights

First seen and last seen timestamps give you the field's usage history. A field with a last seen date three months ago is a different risk than one accessed this week.

### Accessible during schema checks

Field usage data surfaces on the schema check page for fields affected by a proposed change. Assess impact before you publish.

## Evolve your schema with confidence

Start tracking field usage. Deprecate with data. Break nothing you did not mean to.

## FAQ

### Schema Field Usage on Cosmo

- **Where can I access Schema Field Usage?**
- **What information does Schema Field Usage show for each field?**
- **Can I filter by date range?**
- **Do I need client identification set up to use field usage?**
- **Is Schema Field Usage available on the Free plan?**
- **Can I use this data during a schema check?**

Full details in the [schema field usage documentation](https://cosmo-docs.wundergraph.com/studio/analytics/schema-field-usage).