> For the complete documentation index, see [llms.txt](https://docs.stacksync.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.stacksync.com/two-way-sync/features/automatic-sync-configuration-update.md).

# Automatic Sync Configuration Update

### **Overview**

Schema Updates Propagation keeps your sync running as source schemas evolve. You control whether new tables/columns are auto-added and whether deleted tables/columns are automatically removed from the sync mapping. This prevents sync pauses and reduces manual maintenance.

### **I. Schema Change Detection Frequency (Per App)**

* **Enable schema updates**: turns detection on/off for that app.
* **Frequency**: how often Stacksync checks for schema changes (1 hour to 24 hours).
* **Propagate now**: triggers an immediate detection run for that app. Useful when you just made a schema change in an app and want it to be propagated right now.

Notes:

* Detection can occur sooner if schema changes are observed during normal sync runs. This will enable the sync to keep running while otherwise the sync would pause in case a column or table it needs to sync does not exist anymore.

<figure><img src="/files/PzL2gFfBiDwFeDchmSHF" alt=""><figcaption></figcaption></figure>

### **II. When New Tables Are Detected**

In **When the schema of tables already in sync is updated**, configure column-level behavior per table:

* **Do not propagate**: new tables are ignored (recommended if you manage schemas via migrations).
* **Auto-create in target**: new tables detected in the source are created in the target and added to the sync.

You can also add exclusions:

* **Exclude table names** by exact name.
* **Exclude by regex** for patterns (e.g., `^temp_.*`).

Notes:

* Auto-creation is only available if the target system supports creating tables and if the necessary permissions have been set to the user / service account granted access to Stacksync.

<figure><img src="/files/DgS5E8gHKawvfpq0Tswg" alt=""><figcaption></figcaption></figure>

### **III. When Existing Tables Change (Columns)**

In **When the schema of tables already in sync is updated**, configure column-level behavior per table:

* **Add New Columns**: if enabled, a newly detected column in the source is created in the target and added to the sync.
* **Unsync Deleted Columns**: if enabled, deleted source columns are removed from the sync mapping.

<figure><img src="/files/f1Qa0svoixBwIRcE1hj4" alt=""><figcaption></figcaption></figure>

Additional controls by clicking on the gear icon:

* **Column exclusions**: per table, exclude columns by exact name or regex.
* **Default behavior for new tables’ fields**: a default row sets how columns should be handled for tables added later.

<figure><img src="/files/d0yh9e1xTcQGpplmJfmU" alt=""><figcaption></figcaption></figure>

Important:

* Removing a column from the sync does **not** delete the column in the target app; it simply stops syncing it.

#### **Column Renames (Automatic Mapping)**

When a column is renamed in the source app, Stacksync attempts to preserve the sync by matching the column using the app’s immutable field identifiers (when available). This means a rename is treated as the same column with a new name, not as a deletion plus a new column.

What this does:

* Keeps the sync running without manual remapping.
* Avoids creating duplicate columns when only the name changed.
* Applies to apps that expose stable, immutable field IDs.

Notes:

* If the app does not provide immutable field IDs, a rename may be interpreted as “deleted + new” and will follow your column add/remove rules.

### **IV. When Tables Are Deleted**

In **When tables are deleted in an app**, choose the behavior:

* **Auto-unsync deleted tables** (recommended): removes the table from the sync mapping and keeps the sync running.
* **Keep in mapping**: the sync pauses and notifications are sent to workspace collaborators.

Important:

* Auto-unsync does **not** delete the target table in the app. It only stops syncing it.

<figure><img src="/files/tfjkU31AkrJhgMnaSnOC" alt=""><figcaption></figcaption></figure>

If you have any questions, feel free to reach out at *<hello@stacksync.com>*, we are happy to help!