Reimplement system_time triggers in C.

Makefile

@@ -0,0 +1,9 @@
+MODULES = periods
+EXTENSION = periods
+DATA = periods--0.01.sql
+REGRESS = periods
+DOCS = README.periods
+
+PG_CONFIG = pg_config
+PGXS := $(shell $(PG_CONFIG) --pgxs)
+include $(PGXS)

README.periods

@@ -0,0 +1 @@
+README.md

periods--0.01.sql

@@ -757,102 +757,15 @@ $function$;
 
 CREATE FUNCTION periods.generated_always_as_row_start_end()
  RETURNS trigger
- LANGUAGE plpgsql
-AS $function$
-#variable_conflict use_variable
-DECLARE
-    jnew jsonb;
-	start_column_name name;
-    end_column_name name;
-BEGIN
-    SELECT p.start_column_name, p.end_column_name
-    INTO start_column_name, end_column_name
-    FROM periods.periods AS p
-    WHERE (p.table_name, p.period_name) = (TG_RELID, 'system_time');
-
-    IF NOT FOUND THEN
-        RAISE EXCEPTION 'period for SYSTEM_TIME on table "%" not found', TG_TABLE_NAME;
-    END IF;
-
-    /* Set the new timestamps */
-    jnew := row_to_json(NEW);
-    jnew := jsonb_set(jnew, ARRAY[start_column_name], to_jsonb(transaction_timestamp()));
-    jnew := jsonb_set(jnew, ARRAY[end_column_name], to_jsonb('infinity'::timestamp with time zone));
-    RETURN jsonb_populate_record(NEW, jnew);
-END;
-$function$;
+ LANGUAGE c
+ STRICT
+AS 'MODULE_PATHNAME';
 
 CREATE FUNCTION periods.write_history()
  RETURNS trigger
- LANGUAGE plpgsql
- SECURITY DEFINER
-AS $function$
-#variable_conflict use_variable
-DECLARE
-    jnew jsonb;
-    jold jsonb;
-    table_name regclass;
-	start_column_name name;
-    end_column_name name;
-    history_schema_name name;
-    history_table_name name;
-BEGIN
-    /*
-     * If this is not a table with system versioning, just do nothing.  The
-     * trigger exists for all SYSTEM_TIME periods.
-     */
-    IF NOT EXISTS (SELECT FROM periods.system_versioning AS sv WHERE sv.table_name = TG_RELID) THEN
-        RETURN NULL;
-    END IF;
-
-    SELECT p.table_name, p.start_column_name, p.end_column_name
-    INTO table_name, start_column_name, end_column_name
-    FROM periods.periods AS p
-    WHERE (p.table_name, p.period_name) = (TG_RELID, 'system_time');
-
-    IF NOT FOUND THEN
-        RAISE EXCEPTION 'period for SYSTEM_TIME on table "%" not found', TG_TABLE_NAME;
-    END IF;
-
-    IF TG_OP IN ('INSERT', 'UPDATE') THEN
-        jnew := row_to_json(NEW);
-        IF (jnew->>start_column_name)::timestamp with time zone <> transaction_timestamp() THEN
-            RAISE EXCEPTION 'system versioned start column has been tampered with';
-        END IF;
-
-		IF (jnew->>end_column_name)::timestamp with time zone <> 'infinity'::timestamp with time zone THEN
-            RAISE EXCEPTION 'system versioned end column has been tampered with';
-        END IF;
-    END IF;
-
-    IF TG_OP IN ('UPDATE', 'DELETE') THEN
-        jold := row_to_json(OLD);
-		IF (jold->>end_column_name)::timestamp with time zone = transaction_timestamp() THEN
-            /* This row has already been in updated this transaction; do nothing. */
-			RETURN NULL;
-		END IF;
-
-        jold := jsonb_set(jold, ARRAY[end_column_name], to_jsonb(transaction_timestamp()));
-
-        SELECT n.nspname, c.relname
-        INTO history_schema_name, history_table_name
-        FROM periods.system_versioning AS r
-        JOIN pg_class AS c ON c.oid = r.history_table_name
-        JOIN pg_namespace AS n ON n.oid = c.relnamespace
-        WHERE r.table_name = table_name;
-
-        IF NOT FOUND THEN
-            RAISE EXCEPTION 'history table not found';
-        END IF;
-
-        EXECUTE format('INSERT INTO %I.%I VALUES (($1).*)', history_schema_name, history_table_name)
-        USING jsonb_populate_record(OLD, jold);
-    END IF;
-
-    RETURN NULL;
-END;
-$function$;
-
+ LANGUAGE c
+ STRICT
+AS 'MODULE_PATHNAME';
 
 /*
 CREATE FUNCTION periods.add_portion_views(table_name regclass DEFAULT NULL, period_name name DEFAULT NULL)