Skip to content

Postgres schema changes: mention columns are added only after table is updated #4428

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Sep 19, 2025
Merged

Postgres schema changes: mention columns are added only after table is updated #4428

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
33a2b6b
mention column addition only after update happens
Amogh-Bharadwaj Sep 15, 2025
525ab58
fix typo
Amogh-Bharadwaj Sep 15, 2025
cb2ddc3
add line on controlling syncs
Amogh-Bharadwaj Sep 15, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion docs/integrations/data-ingestion/clickpipes/postgres/faq.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@ To set the replica identity to FULL, you can use the following SQL command:
```sql
ALTER TABLE your_table_name REPLICA IDENTITY FULL;
```
REPLICA IDENTITY FULL also enabled replication of unchanged TOAST columns. More on that [here](./toast).
REPLICA IDENTITY FULL also enables replication of unchanged TOAST columns. More on that [here](./toast).

Note that using `REPLICA IDENTITY FULL` can have performance implications and also faster WAL growth, especially for tables without a primary key and with frequent updates or deletes, as it requires more data to be logged for each change. If you have any doubts or need assistance with setting up primary keys or replica identities for your tables, please reach out to our support team for guidance.

Expand Down
6 changes: 4 additions & 2 deletions docs/integrations/data-ingestion/clickpipes/postgres/schema-changes.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,8 @@

| Schema Change Type | Behaviour |
| ----------------------------------------------------------------------------------- | ------------------------------------- |
| Adding a new column (`ALTER TABLE ADD COLUMN ...`) | Propagated automatically. The new column(s) 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. The new column(s) will be populated for all rows replicated after the schema change, but existing rows will not show the default value without a full table refresh |
| Adding a new column (`ALTER TABLE ADD COLUMN ...`) | Propagated automatically once the table gets an insert/update/delete. The new column(s) will be populated for all rows replicated after the schema change |

Check warning on line 13 in docs/integrations/data-ingestion/clickpipes/postgres/schema-changes.md

View workflow job for this annotation

GitHub Actions / vale

ClickHouse.FutureTense 

Instead of future tense 'will be', use present tense.

Check warning on line 13 in docs/integrations/data-ingestion/clickpipes/postgres/schema-changes.md

View workflow job for this annotation

GitHub Actions / vale

ClickHouse.BadPlurals 

Rewrite '(s)' to be plural without parentheses.
| 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 column(s) will be populated for all rows replicated after the schema change, but existing rows will not show the default value without a full table refresh |
| Dropping an existing column (`ALTER TABLE DROP COLUMN ...`) | Detected, but **not** propagated. The dropped column(s) 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](./controlling_sync.md)