boundary/internal/db/schema/migrations/postgres/2/01_log.up.sql

begin;

-- log_migration entries represent logs generated during migrations
create table log_migration(
  id bigint generated always as identity primary key,
  migration_version bigint not null, -- cannot declare FK since the table is truncated during runtime
  create_time wt_timestamp,
  entry text not null
);
comment on table log_migration is 
'log_migration entries are logging output from databaes migrations';

-- log_migration triggers
create trigger 
  default_create_time_column
before
insert on log_migration
  for each row execute procedure default_create_time();

create trigger
  immutable_columns
before
update on log_migration
  for each row execute procedure immutable_columns('id', 'migration_version', 'create_time', 'entry');


-- log_migration_version() defines a function to be used in a "before update"
-- trigger for log_migrations entries.  Its intent: set the log_migration
-- version column to the current migration version.  
create or replace function
  log_migration_version()
  returns trigger
as $$
  declare current_version bigint;
  begin
    select max(version) from boundary_schema_version into current_version;
    new.migration_version = current_version;
    return new;
  end;
$$ language plpgsql;
comment on function log_migration_version() is
'log_migration_version will set the log_migration entries to the current migration version';    

create trigger
  migration_version_column
before
insert on log_migration
  for each row execute procedure log_migration_version();

  commit;