remove half-baked object detection schema

I want to release schema version 6 now, with the fully developed pieces.

db/raw.rs

@@ -271,12 +271,6 @@ pub(crate) fn delete_recordings(tx: &rusqlite::Transaction, sample_file_dir_id:
           :start <= composite_id and
           composite_id < :end
     "#)?;
-    let mut del_detection = tx.prepare_cached(r#"
-        delete from recording_object_detection
-        where
-          :start <= composite_id and
-          composite_id < :end
-    "#)?;
     let mut del_main = tx.prepare_cached(r#"
         delete from recording
         where
@@ -300,9 +294,6 @@ pub(crate) fn delete_recordings(tx: &rusqlite::Transaction, sample_file_dir_id:
     if n_integrity > n {  // fewer is okay; recording_integrity is optional.
         bail!("inserted {} garbage rows but deleted {} recording_integrity rows!", n, n_integrity);
     }
-    // Any number of object detection rows is okay, as there can be zero or more models per
-    // recording.
-    del_detection.execute_named(p)?;
     let n_main = del_main.execute_named(p)?;
     if n_main != n {
         bail!("inserted {} garbage rows but deleted {} recording rows!", n, n_main);

db/schema.sql

@@ -519,45 +519,5 @@ create table signal_change (
   changes blob not null
 );
 
-create table object_detection_model (
-  id integer primary key,
-  uuid blob unique not null check (length(uuid) = 16),
-  name text not null,
-
-  -- The actual model and label mappings, in a tbd protocol buffer message
-  -- format.
-  data blob
-);
-
--- An entry for every supported label in any model. (E.g., there is one row
--- for "person" even if there are many models that support detecting people.)
-create table object_detection_label (
-  id integer primary key,
-  uuid blob unique not null check (length(uuid) = 16),
-  name text unique not null,
-  color text
-);
-
-create table recording_object_detection (
-  composite_id integer not null references recording (composite_id),
-  model_id integer not null references object_detection_model (id),
-
-  -- repeated:
-  -- * frame delta unsigned varint
-  -- * label unsigned varint
-  -- * xmin, xmax, ymin, ymax as fixed 8-bit numbers
-  --   (any value from knowing xmin <= xmax, ymin <= ymax?
-  --   probably not a whole byte anyway.)
-  --   although 256/300 or 256/320 is not super clean. awkward.
-  -- * score/probability/whatever-it's-called as fixed 8-bit number
-  --   linear scale?
-  frame_data blob not null,
-
-  -- Operations are almost always done on a bounded set of recordings, so
-  -- and perhaps on all models. Use composite_id as the prefix of the primary
-  -- key to make these efficient.
-  primary key (composite_id, model_id)
-);
-
 insert into version (id, unix_time,                           notes)
              values (6,  cast(strftime('%s', 'now') as int), 'db creation');

db/upgrade/v5_to_v6.rs

@@ -328,27 +328,6 @@ pub fn run(_args: &super::Args, tx: &rusqlite::Transaction) -> Result<(), Error>
           revocation_reason_detail = 'Blake2b->Blake3 upgrade'
         where
           revocation_reason is null;
-
-        create table object_detection_model (
-          id integer primary key,
-          uuid blob unique not null check (length(uuid) = 16),
-          name text not null,
-          data blob
-        );
-
-        create table object_detection_label (
-          id integer primary key,
-          uuid blob unique not null check (length(uuid) = 16),
-          name text unique not null,
-          color text
-        );
-
-        create table recording_object_detection (
-          composite_id integer not null references recording (composite_id),
-          model_id integer not null references object_detection_model (id),
-          frame_data blob not null,
-          primary key (composite_id, model_id)
-        );
     "#)?;
     Ok(())
 }

guide/schema.md

@@ -252,8 +252,6 @@ Version 6 adds over version 5:
     streams.
 *   hashes in Blake3 rather than older SHA-1 (for file integrity checksums)
     or Blake2b (for sessions).
-*   a preliminary schema for [object
-    detection](https://en.wikipedia.org/wiki/Object_detection).
 *   for each recording row, the cumulative total duration and "runs" recorded
     before it on that stream. This is useful for MediaSourceExtension-based
     web browser UIs when setting timestamps of video segments in the