-- these exist for all posts
  --
  id integer primary key AUTOINCREMENT,
  type integer not null check (type >= 0 AND type <= 5 ),
  -- milliseconds since UNIX Epoch
  timestamp integer not null check (timestamp > 0),
  -- depends on postType
  -- join & leave don't have other fields then channel
  text text,
  topic text,
  deletedHashes blob,    -- concatenated
  -- `post/text`  | a textual chat message, posted to a channel |
  CONSTRAINT is_text check (
    type != 0 OR (channel is not null AND text is not null)
  ),
  -- `post/delete`| the deletion of a previously published post |
  CONSTRAINT is_delete check (
    type != 1 OR (deletedHashes is not null)
  ),
  -- `post/info`  | set or clear informative key/value pairs on a user
  CONSTRAINT is_info check (
  ),
  -- `post/topic` | set or clear a channel's topic string
  CONSTRAINT is_topic check (
    type != 3 OR (channel is not null AND topic is not null)
  ),
  -- `post/join`  | announce membership to a channel
  CONSTRAINT is_join check (
    type != 4 OR (channel is not null)
  ),
  -- `post/leave` | announce cessation of membership to a channel
  CONSTRAINT is_leave check (
    type != 5 OR (channel is not null)
);
    source blob not null,
);
CREATE INDEX IF NOT EXISTS parent_idx ON links(parent);
    -- we will get posts for which we don't have the parent's (yet)
    -- foreign key(source) references posts(hash),
    -- foreign key(parent) references posts(hash),
    parent blob not null
create table IF NOT EXISTS links (
    channel text,
  ),
  foreign key(user_id) references users(id)
    type != 2 OR (infos is not null)
  infos blob,            -- encoded as (json?) map {k=>v, k=>v}
  channel text,          -- all but delete have this one
  user_id integer not null,
  raw_post blob not null,
  hash blob unique not null check (length(hash) = 32),
create table IF NOT EXISTS posts (

    %% read posts and links schema and exec it
    PrivDir = code:priv_dir(cable),
    SchemaPath = filename:join(PrivDir, "schema.sql"),
    {ok, Schema} = file:read_file(SchemaPath),

    %% Embedded schema - more reliable than code:priv_dir/1
    Schema = <<"
create table IF NOT EXISTS posts (
  -- these exist for all posts
  --
  id integer primary key AUTOINCREMENT,
  hash blob unique not null check (length(hash) = 32),
  type integer not null check (type >= 0 AND type <= 5 ),
  -- milliseconds since UNIX Epoch
  timestamp integer not null check (timestamp > 0),
  user_id integer not null,
  raw_post blob not null,
  -- depends on postType
  channel text,          -- all but delete have this one
  -- join & leave don't have other fields then channel
  text text,
  topic text,
  deletedHashes blob,    -- concatenated
  infos blob,            -- encoded as (json?) map {k=>v, k=>v}
  -- `post/text`  | a textual chat message, posted to a channel |
  CONSTRAINT is_text check (
    type != 0 OR (channel is not null AND text is not null)
  ),
  -- `post/delete`| the deletion of a previously published post |
  CONSTRAINT is_delete check (
    type != 1 OR (deletedHashes is not null)
  ),
  -- `post/info`  | set or clear informative key/value pairs on a user
  CONSTRAINT is_info check (
    type != 2 OR (infos is not null)
  ),
  -- `post/topic` | set or clear a channel's topic string
  CONSTRAINT is_topic check (
    type != 3 OR (channel is not null AND topic is not null)
  ),
  -- `post/join`  | announce membership to a channel
  CONSTRAINT is_join check (
    type != 4 OR (channel is not null)
  ),
  -- `post/leave` | announce cessation of membership to a channel
  CONSTRAINT is_leave check (
    type != 5 OR (channel is not null)
  ),
  foreign key(user_id) references users(id)
);
create table IF NOT EXISTS links (
    channel text,
    source blob not null,
    parent blob not null
    -- we will get posts for which we don't have the parent's (yet)
    -- foreign key(source) references posts(hash),
    -- foreign key(parent) references posts(hash),
);
CREATE INDEX IF NOT EXISTS parent_idx ON links(parent);
">>,

    % Start required applications
    ok = application:ensure_started(crypto),
    ok = application:ensure_started(asn1),
    ok = application:ensure_started(public_key),
    ok = application:ensure_started(ssl),