Preview
Before starting a clone, Twins analyzes your source project to show you exactly what will be copied. This step helps you avoid surprises.
What You See
Tables
For each table in the source project:
- Name and schema (e.g.,
public.users) - Number of columns
- Number of rows (approximate)
You can click on a table to view column details: name, data type, default value, and whether it is nullable.
Functions and Triggers
- Name of each function, schema, and language (plpgsql, sql, etc.)
- Name of each trigger and its associated table
RLS Policies
- Name of each policy
- Associated table
- Operation type (SELECT, INSERT, UPDATE, DELETE)
Edge Functions
- List of functions deployed on the source project
Storage
- Name of each bucket
- Number of files (approximate)
Auth Users
- Total number of user accounts
Cron Jobs and Webhooks
- Schedule and command for each cron job
- Name and events for each webhook
Warnings
The preview generates warnings to alert you to noteworthy situations:
| Warning | Meaning |
|---|---|
| Large table | More than 100,000 rows — cloning will take longer |
| Empty table | The table exists but contains no rows |
| Missing extension | The source uses an extension that is not available on the target |
| Cross-schema FK | A foreign key references a table in a different schema |
Source / Target Comparison
If the target project already contains data (for example, during a re-clone), the preview shows a diff:
- Tables present in the source but missing from the target
- Differences in row counts
- Columns added or removed
This helps you understand the impact of the clone before starting it.
Using the Preview to Decide
The preview is the ideal place to:
- Verify that all your objects are detected
- Identify large tables you may want to exclude
- Anticipate potential issues (missing extensions, conflicts)
- Adjust your clone options accordingly
Next Steps
- Clone Options — Customize your clone
- Creating a Clone — Start the clone after the preview