> ## Documentation Index
> Fetch the complete documentation index at: https://docs.paradedb.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Schema Changes

> Handle DDL/schema changes when running ParadeDB as a logical replica

<Note>
  This section assumes that you have successfully completed the [getting
  started](/deploy/logical-replication/getting-started) guide and reviewed the
  [Logical Replication Operational
  Guide](/deploy/logical-replication/operational-guide).
</Note>

## Schema Changes

PostgreSQL logical replication copies row changes, not DDL. That means schema
changes on the publisher are not applied automatically on ParadeDB.

Keep these rules in mind:

* Existing replicated tables must stay schema-compatible on both sides
* New tables must exist on ParadeDB before they can replicate there
* BM25 indexes are local to ParadeDB and must be created or rebuilt there
* Publication membership still controls whether a new table is replicated at all

```sql theme={null}
-- On Publisher
ALTER TABLE mock_items ADD COLUMN num_stock int;
INSERT INTO mock_items (description, category, in_stock, latest_available_time, last_updated_date, metadata, created_at, rating, num_stock)
VALUES ('Green running shoes', 'Footwear', true, '14:00:00', '2024-07-09', '{}', '2024-07-09 14:00:00', 2, 900);

-- On Subscriber
ERROR: logical replication target relation "public.mock_items" is missing some replicated columns
```

For the safe rollout sequence, including subscriber-first additive DDL and how
to handle non-additive changes, see [Roll Out DDL
Safely](/deploy/logical-replication/operational-guide#roll-out-ddl-safely).

If replication is already failing because the schemas diverged or because a
conflict stopped the apply worker, see [Troubleshoot Apply
Failures](/deploy/logical-replication/operational-guide#troubleshoot-apply-failures).

If you want a new table to replicate to ParadeDB, that table must be included
in the publication. Publications created with `FOR ALL TABLES` include new
tables automatically, and publications created with `FOR TABLES IN SCHEMA ...`
include new tables created in those schemas automatically. If your publication
was created from an explicit table list, new tables will not replicate until
you add them manually. If you do not want a table replicated to ParadeDB, leave
it out of the publication.

For the full sequence for adding a replicated searchable table, see [Add New
Tables](/deploy/logical-replication/operational-guide#add-new-tables).

```sql theme={null}
-- On Publisher
ALTER PUBLICATION marketplace_pub ADD TABLE newly_added_table;

-- On Subscriber
ALTER SUBSCRIPTION marketplace_sub REFRESH PUBLICATION;
```