Remove Event Triggers

Removing Event Triggers

Event Triggers can be removed using the Hasura Console, Hasura CLI, or Metadata APIs.

Console

Open the Hasura Console, head to the Events tab, click on the Event Trigger you want to delete, and click on the Delete Event Trigger button at the bottom of the page:

CLI

You can remove an Event Trigger for a table by updating the databases > [source-name] > tables > [table-name].yaml file inside the metadata directory and removing the event trigger from it:

- table:
   schema: public
   name: author
event_triggers:
   - name: author_trigger
   definition:
      enable_manual: false
      insert:
         columns: "*"
      update:
         columns: "*"
   webhook: https://httpbin.org/post

Apply the Metadata by running:

hasura metadata apply

API

You can delete Event Triggers by using the appropriate Metadata API, either: pg_delete_event_trigger or mssql_delete_event_trigger.

To delete an Event Trigger via the the Metadata API, replace <db_type_delete_event_trigger> with the following:

• Postgres: pg_delete_event_trigger
• MSSQL: mssql_delete_event_trigger

POST /v1/metadata HTTP/1.1
Content-Type: application/json
X-Hasura-Role: admin

{
   "type" : "<db_type_delete_event_trigger>",
   "args" : {
        "name": "author_trigger",
        "source": "default"
    }
}

Event Triggers for a table or source will also get dropped if the corresponding table/source is dropped.

Warning

An Event Trigger can be removed using the above methods (Delete Event Trigger, Drop Table or Drop Source) only when the metadata is consistent.

If the metadata is inconsistent, then an Event Trigger can be dropped using "Replace Metadata" or "Clear Metadata" methods. This may leave some footprint in the source which can be cleaned manually as described in the following section.

Clean up Event Trigger footprints manually

When an Event Trigger is created, Hasura creates SQL triggers on the table corresponding to each database operation (INSERT/UPDATE/DELETE) described in the Event Trigger configuration.

When an inconsistent Table/Event Trigger is removed via the replace_metadata API, it may leave orphaned SQL triggers in the database. The following command can be used to manually delete SQL triggers corresponding to an Event Trigger on a table:

DROP FUNCTION hdb_catalog."notify_hasura_<event-trigger-name>_<OPERATION-NAME>" CASCADE;

For example: to delete SQL triggers corresponding to an Event Trigger: users_all on a table: users with operation: INSERT in the Event Trigger configuration:

DROP FUNCTION hdb_catalog."notify_hasura_users_all_INSERT" CASCADE;

Deleting all triggers

The SQL trigger should be deleted for each operation mentioned in the Event Trigger configuration, i.e. INSERT/UPDATE/DELETE

Clean up Hasura footprints from a source manually

When a source in an inconsistent state is dropped, it may leave Hasura footprints in the database due to Event Triggers. The following can be used to remove all footprints of Event Triggers present in a source from the database:

Case 1: When using a different Metadata database to the source database

In this case, hdb_metadata table is not present in hdb_catalog schema of the source.

To clean up Hasura footprint completely, drop the hdb_catalog schema:

DROP SCHEMA IF EXISTS hdb_catalog;

Case 2: When the Metadata database and source database are the same

In this case, a hdb_metadata table is present in the hdb_catalog schema of the source. You may want to preserve the Metadata but remove the remaining Hasura footprint of a few tables for Event Triggers and corresponding SQL triggers.

Step 1: In order to drop the SQL triggers corresponding to Event Triggers created, please refer to the clean up Event Trigger footprints manually section. Alternatively, the following command can be used to drop all SQL triggers in the source:

do $$
declare f record;
begin
  for f in select trigger_name, event_object_table
    from information_schema.triggers
    where trigger_name like 'notify_hasura_%'
  loop
    EXECUTE 'DROP FUNCTION hdb_catalog.' || QUOTE_IDENT(f.trigger_name) || ' CASCADE';
  end loop;
end;
$$;

Step 2: The following commands can be used to delete Event Triggers tables from hdb_catalog:

DROP TABLE IF EXISTS hdb_catalog.hdb_source_catalog_version;
DROP FUNCTION IF EXISTS hdb_catalog.insert_event_log(text, text, text, text, json);
DROP TABLE IF EXISTS hdb_catalog.event_invocation_logs;
DROP TABLE IF EXISTS hdb_catalog.event_log;
DROP TABLE IF EXISTS hdb_catalog.hdb_event_log_cleanups;

Execute as single transaction

It is recommended to perform the above steps in a single transaction.