Archive mode for interning

temporal.sql

@@ -4,6 +4,7 @@ CREATE SCHEMA IF NOT EXISTS temporal;
 COMMENT ON SCHEMA temporal IS 'Upgrade any table with state tracking.';
 SET LOCAL search_path TO temporal, public;
 
+
 CREATE TABLE state (
   txid      bigint NOT NULL DEFAULT txid_current(),
   t         timestamptz NOT NULL DEFAULT now(),
@@ -16,30 +17,42 @@ COMMENT ON TABLE state IS
 CREATE INDEX "state/txid" ON state (txid);
 CREATE INDEX "state/t" ON state (t);
 
+
+CREATE TYPE mode AS ENUM ('only_old', 'only_new', 'old_and_new');
+
+
 CREATE FUNCTION temporal(tab regclass,
                          state_schema name DEFAULT NULL,
                          state_tab name DEFAULT NULL,
-                         with_old boolean DEFAULT FALSE)
+                         mode mode DEFAULT 'only_new')
 RETURNS regclass AS $$
+DECLARE
+  txt text;
 BEGIN
-  EXECUTE temporal.codegen(tab, state_schema, state_tab, with_old);
+  FOR txt IN SELECT * FROM temporal.codegen(tab, state_schema, state_tab, mode)
+  LOOP
+    EXECUTE txt;
+  END LOOP;
   RETURN (SELECT states FROM temporal.logged
            WHERE temporal.logged.logged = tab);
 END
 $$ LANGUAGE plpgsql;
-COMMENT ON FUNCTION temporal(regclass, name, name, boolean) IS
+COMMENT ON FUNCTION temporal(regclass, name, name, mode) IS
  'Configures triggers and a state table to provide row versioning.';
 
+
 CREATE FUNCTION codegen(tab regclass,
                         state_schema name DEFAULT NULL,
                         state_tab name DEFAULT NULL,
-                        with_old boolean DEFAULT FALSE)
-RETURNS text AS $code$
+                        mode mode DEFAULT 'only_new')
+RETURNS TABLE (statement text) AS $code$
 DECLARE
-  entity_type text;
-  entity_pk   text;
   fullname    text;
-  code        text := '';
+  code        text[] := ARRAY[]::text[];
+  tabledef    text[] := ARRAY[]::text[];
+  fielddef    text[] := ARRAY[]::text[];
+  valuedef    text[] := ARRAY[]::text[];
+  eventdef    text[] := ARRAY[]::text[];
 BEGIN
   state_schema := COALESCE(state_schema, meta.schemaname(tab));
   IF state_schema = meta.schemaname(tab) THEN
@@ -53,62 +66,71 @@ BEGIN
     RAISE EXCEPTION 'It looks like we''re trying to create a state table '
                     'with the same name and schema as the base table.';
   END IF;
-  code := code || $$
-    CREATE SCHEMA IF NOT EXISTS $$||quote_ident(state_schema)||$$;
-  $$;
-
-  IF with_old THEN
-    code := code || $$
-      CREATE TABLE $$||fullname||$$ (
-        LIKE temporal.state INCLUDING INDEXES INCLUDING DEFAULTS,
-        new jsonb,
-        old jsonb
-      ) INHERITS (temporal.state);
-      CREATE FUNCTION temporal.save($$||tab||$$, $$||tab||$$)
-      RETURNS $$||fullname||$$ AS $f$
-        INSERT INTO $$||fullname||$$ (new, old)
-        VALUES (row_to_json($1)::jsonb, row_to_json($2)::jsonb)
-        RETURNING *
-      $f$ LANGUAGE sql;
-    $$;
-  ELSE
-    code := code || $$
-      CREATE TABLE $$||fullname||$$ (
-        LIKE temporal.state INCLUDING INDEXES INCLUDING DEFAULTS,
-        new jsonb
-      ) INHERITS (temporal.state);
-      CREATE FUNCTION temporal.save($$||tab||$$, $$||tab||$$)
-      RETURNS $$||fullname||$$ AS $f$
-        INSERT INTO $$||fullname||$$ (new) VALUES (row_to_json($1)::jsonb)
-        RETURNING *
-      $f$ LANGUAGE sql;
-    $$;
+
+  IF mode NOT IN ('only_old') THEN
+    tabledef := tabledef || ARRAY['new_tid tid', 'new jsonb'];
+    fielddef := fielddef || ARRAY['new_tid',  'new'];
+    valuedef := valuedef || ARRAY['$1', 'row_to_json($2)::jsonb'];
+    eventdef := ARRAY['INSERT', 'UPDATE', 'DELETE'];
   END IF;
 
-  code := code || $$
-    CREATE TRIGGER temporal AFTER INSERT OR UPDATE OR DELETE
-        ON $$||tab||$$
+  IF mode NOT IN ('only_new') THEN
+    tabledef := tabledef || ARRAY['old_tid tid', 'old jsonb'];
+    fielddef := fielddef || ARRAY['old_tid',  'old'];
+    valuedef := valuedef || ARRAY['$3', 'row_to_json($4)::jsonb'];
+    eventdef := ARRAY['UPDATE', 'DELETE'];
+  END IF;
+
+  code := code || ARRAY[$$
+    CREATE SCHEMA IF NOT EXISTS $$||quote_ident(state_schema)||$$;
+  $$];
+
+  code := code || ARRAY[$$
+    CREATE TABLE $$||fullname||$$ (
+      LIKE temporal.state INCLUDING INDEXES INCLUDING DEFAULTS,
+      $$||array_to_string(tabledef, ', ')||$$
+    ) INHERITS (temporal.state);
+  $$];
+
+  code := code || ARRAY[$$
+    CREATE FUNCTION temporal.save(tid, $$||tab||$$, tid, $$||tab||$$)
+    RETURNS $$||fullname||$$ AS $save$
+      INSERT INTO $$||fullname||$$ ($$||array_to_string(fielddef, ', ')||$$)
+      VALUES ($$||array_to_string(valuedef, ', ')||$$)
+      RETURNING *
+    $save$ LANGUAGE sql;
+  $$];
+
+  code := code || ARRAY[$$
+    CREATE TRIGGER temporal
+     AFTER $$||array_to_string(eventdef, ' OR ')||$$ ON $$||tab||$$
        FOR EACH ROW EXECUTE PROCEDURE temporal.save();
-  $$;
-  --- Clean up all the whitespace in the generated SQL.
-  code := regexp_replace(code, '\n[ ]*$', '', 'g');
-  code := regexp_replace(code, '^    ',   '', 'gn');
-  RETURN code;
+  $$];
+
+  FOREACH statement IN ARRAY code LOOP
+    --- Clean up all the whitespace in the generated SQL.
+    statement := regexp_replace(statement, '^\n', '', 'g');
+    statement := regexp_replace(statement, '[ ]*$', '', 'g');
+    statement := regexp_replace(statement, '^    ',   '', 'gn');
+    RETURN NEXT;
+  END LOOP;
 END
 $code$ LANGUAGE plpgsql;
 
+
 CREATE FUNCTION save() RETURNS trigger AS $$
 BEGIN
   --- Dispatches to appropriate save function based on row type.
   CASE TG_OP
-  WHEN 'INSERT' THEN PERFORM temporal.save(NEW, NULL);
-  WHEN 'UPDATE' THEN PERFORM temporal.save(NEW, OLD);
-  WHEN 'DELETE' THEN PERFORM temporal.save(NULL, OLD);
+  WHEN 'INSERT' THEN PERFORM temporal.save(NEW.ctid, NEW, NULL, NULL);
+  WHEN 'UPDATE' THEN PERFORM temporal.save(NEW.ctid, NEW, OLD.ctid, OLD);
+  WHEN 'DELETE' THEN PERFORM temporal.save(NULL, NULL, OLD.ctid, OLD);
   END CASE;
   RETURN NULL;
 END
 $$ LANGUAGE plpgsql;
 
+
 CREATE VIEW logged AS
 SELECT logged.oid::regclass AS logged,
        states.oid::regclass AS states