# Real-time 2.0 Configuration and Initialization

## Overview

Configuration and initialization in Real-Time 2.0 cover how you set up identity stitching, define events and attributes, and prepare batch data for use in real-time. This section outlines the key behaviors, limits, and best practices to help you configure Real-Time 2.0 correctly from the start.

| Category | Limit / Behavior | Notes |
|  --- | --- | --- |
| ID Stitching Keys | Up to 100 IDs can be defined as stitching keys | Examples: email, user_id, td_client_id. Used to link events to profiles. |
| Batch ID Sync (Initialization) | Optional. Batch ID graphs can be imported into real-time to ensure continuity | Recommended when existing batch identities need to be available in real-time. |
| Profile Key (Primary ID) | Defined at Parent Segment creation; cannot be changed later | Determines the main join key across batch and real-time data. |
| Event Tables | Maximum 100 event tables per Parent Segment | Applies to both batch and real-time event tables. |
| Event Definitions | No hard limit | Aggregate filter length across definitions must be ≤1000 characters. |
| Attribute Backfill | Supported for batch attributes | Use backfill to pre-populate RT attributes with values from existing batch data. |
| Importing Batch Attributes | Supported | Newly added fields in batch tables become available after segment refresh. |
| New Event Fields | Automatically available in the database | Must be explicitly configured as RT attributes to use in personalization or triggers. |
| Multi-Account Deployment | Supported via CI/CD pipeline | Configurations can be exported from one environment and reused in another. |


## Expected Behavior

- Batch ID Sync: Not mandatory, but recommended when migrating existing batch identities into real-time.
- Profile Keys: Chosen during Parent Segment setup and remain fixed afterward.
- Attributes: Backfill lets you populate RT attributes with historical values. New fields automatically flow into the system but require explicit configuration to be used in activations or personalization.
- Deployment Across Accounts: Supported through CI/CD processes to ensure consistent configuration across multiple environments.


## Notes & Recommendations

- Plan your profile key strategy before enabling real-time to avoid rework.
- Use attribute backfill when enabling real-time for existing batch segments.
- Manage configurations with CI/CD to simplify multi-environment deployments.
- Regularly review new batch or event fields to decide if they should be promoted as RT attributes.