> ## Documentation Index > Fetch the complete documentation index at: https://docs.kadoa.com/llms.txt > Use this file to discover all available pages before exploring further. # Change Detection > How Kadoa detects and classifies data changes between workflow runs To enable change detection, two things are **required**: 1. Your workflow must be scheduled (hourly, daily, etc.) or set to real-time mode. Configure scheduling in the [UI](/docs/ui/workflows/sources) or via [Code](/docs/sdk/workflows/create). 2. Your workflow must subscribe to the data change event. Without this subscription, change diffs will not be delivered. Make sure both conditions are met for change tracking to function. ## Workflow Modes | Mode | How It Works | Availability | | ------------- | -------------------------------------------------- | ------------ | | **Scheduled** | Compares data between runs (hourly, daily, weekly) | All plans | | **Real-time** | Continuously monitors for changes | All plans | Both modes use the same change detection algorithm described below. ## Algorithm Overview The change detection process follows a **three-phase matching algorithm**: 1. **Exact Matches**: Objects that are completely identical (with whitespace normalization) 2. **Partial Matches**: Objects that are similar enough to be considered the same but with changes 3. **Leftovers**: Remaining objects classified as either new or removed ## Matching Methods ### Key Field Matching (Optional) When **key fields** are configured in your schema, objects are matched based on these fields. **ALL key fields must match** for objects to be considered the same: ```json theme={null} // Previous run { "id": "12345", "title": "Product A", "price": "$100" } // Current run { "id": "12345", // Key field matches "title": "Product A Pro", // Changed "price": "$150" // Changed } ``` **Result**: `changed` - ID matches, so same object with updates **Key Field Behavior**: * Key fields defined with `isKey: true` in your [schema](/docs/workflows/schemas) * Common key fields: `id`, `url`, `link`, `sku` * Key fields should use scalar `STRING`, `NUMBER`, or `LINK` types * If ANY key field changes, objects treated as `removed` + `added` (not `changed`) ### Traditional Field Matching (Default) When no key fields are configured, objects are matched if they share **>50% of their fields**: ```json theme={null} // Previous run { "name": "John Doe", "age": "25", "city": "New York" } // Current run { "name": "John Doe", // Same "age": "26", // Changed "city": "New York" // Same } ``` **Field Match Calculation**: 2 out of 3 fields match = 66.7% > 50% **Result**: `changed` - Field match ratio exceeds threshold **Notes**: * Only string fields considered in ratio calculation * Empty fields and non-string values excluded ## Change Types | Type | Description | | ----------- | ---------------------------------------------------------- | | **Changed** | Object matched but some fields differ | | **Added** | Object exists in current run but no match in previous run | | **Removed** | Object existed in previous run but no match in current run | ## How Changes Appear ### In the UI View detected changes directly in your workflow's run history: 1. Open your workflow 2. Click the **History** tab on the right-hand side 3. Find a run with data changes 4. Click on the **Diff** component to view changes The diff view displays: * Change type indicators (added, removed, changed) * Visual diff highlighting for modified fields * Timestamps for when changes were detected Data Changes View See [Data Delivery](/docs/integrations/overview) for notification channels, APIs, and payload formats. ## Method Comparison | Method | When Used | Logic | Best For | | ---------------------------------- | ----------------------------------------------------------- | --------------------------------- | ------------------------------------------------- | | **Key Field Matching** | Set `isKeyField: true` in [schema](/docs/workflows/schemas) | ALL key fields must match exactly | Reliable matching even with major content changes | | **Traditional Matching** (Default) | No key fields configured | >50% of fields must match | Simple setup, works without configuration | ## Setup Data Change ### Fields Select which fields from your [schema](/docs/workflows/schemas) to monitor. Only changes to selected fields will trigger notifications. By default, Kadoa monitor all fields. ### Change Types Choose which types of changes to track: | Type | Description | | ----------- | ---------------------------- | | **Changed** | Existing record was modified | | **Added** | New record appeared | | **Removed** | Record no longer exists | ### Conditions Add conditions to filter notifications based on field values. Combine multiple conditions using logical operators. **Logical Operators:** * **Any** (OR): Notify if any condition matches * **All** (AND): Notify only if all conditions match **Available Operators:** | Operator | Description | Example | | ------------------ | ------------------------- | -------------------------------- | | `contains` | Field value contains text | title contains "sale" | | `does not contain` | Field value excludes text | title does not contain "expired" | | `equals` | Exact match | status equals "active" | | `does not equal` | Does not match | status does not equal "draft" | | `greater than` | Numeric comparison | price greater than 100 | | `less than` | Numeric comparison | stock less than 10 | | `before` | Date is before value | published before 2025-01-01 | | `after` | Date is after value | published after 2025-01-01 | | `in the last` | Date within N days | published in the last 7 days | | `is empty` | Field has no value | description is empty | | `is not empty` | Field has a value | price is not empty | ### Date Filtering Use `before`, `after`, or `in the last` operators to filter changes by date. Useful for monitoring news feeds or content where you only care about recent updates. Your data must include a date field for date filtering to work. **Supported Date Formats:** * ISO: `2025-01-15` (recommended) * US/EU: `01/15/2025`, `15/01/2025` * Month names: `Jan 15, 2025` * Timestamps: `2025-01-15T10:30:00Z` ## Retrieve Historical Changes View change history for your monitoring workflows. 1. Open your workflow 2. Click the **History** tab 3. Select a run to view its changes Change History The `/changes` endpoint returns all historical data changes. [View full API reference →](/api-reference/monitoring/get-all-changes) ```bash theme={null} GET https://api.kadoa.com/v4/changes ``` Filter by workflow and date range: ```bash theme={null} GET https://api.kadoa.com/v4/changes?startDate=2024-11-01T00:00:00Z&endDate=2024-11-30T23:59:59Z ``` ### Response Format Each change includes a `differences` array: ```json theme={null} { "differences": [ { "type": "changed", "fields": [ { "key": "title", "previousValue": "Old Title", "value": "New Title" } ] } ] } ``` **`differences` structure:** * `type`: Change type (`added`, `removed`, or `changed`) * `fields`: All fields of the object **Field change properties:** * `key`: Field name * `value`: Current value * `previousValue`: Previous value (only for `changed` type)