> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-8a08bda2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Schema changes propagation support

> Page describing schema change types detectable by ClickPipes in the source tables

ClickPipes for Postgres can detect schema changes in the source tables and, in some cases, automatically propagate the changes to the destination tables. The way each DDL operation is handled is documented below:

[//]: # "TODO Extend this page with behavior on rename, data type changes, and truncate + guidance on how to handle incompatible schema changes."

| Schema Change Type                                                                  | Behaviour                                                                                                                                                                                                                            |
| ----------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| Adding a new column (`ALTER TABLE ADD COLUMN ...`)                                  | Propagated automatically once the table gets an insert/update/delete. The new columns will be populated for all rows replicated after the schema change                                                                              |
| Adding a new column with a default value (`ALTER TABLE ADD COLUMN ... DEFAULT ...`) | Propagated automatically once the table gets an insert/update/delete. The new columns will be populated for all rows replicated after the schema change, but existing rows won't show the default value without a full table refresh |
| Dropping an existing column (`ALTER TABLE DROP COLUMN ...`)                         | Detected, but **not** propagated. The dropped columns will be populated with `NULL` for all rows replicated after the schema change                                                                                                  |

Note that column addition will be propagated at the end of a batch's sync, which could occur after the sync interval or pull batch size is reached. More information on controlling syncs [here](/integrations/clickpipes/postgres/controlling-sync)