create table projection_field_sources (
  topic text not null,
  path text not null,
  filter text not null
);
comment on table projection_field_sources is '
  Represents the source for a single projection field from a topic's schema.
';

comment on column projection_field_sources.topic is '
  Name of the originating topic.
';
comment on column projection_field_sources.path is '
  A slimmed down variant of [JSON Path](https://gregsdennis.github.io/Manatee.Json/usage/path.html) to point to a specific field in a topic's schema.
';
comment on column projection_field_sources.filter is '
  A conditional filter expression. The expression can contain variables, which will be passed in when evaluating the projection.
';