diff --git a/diagrams/erdiagram_targetdb_latest.pdf b/diagrams/erdiagram_targetdb_latest.pdf
index 7c8341f..db3c921 100644
Binary files a/diagrams/erdiagram_targetdb_latest.pdf and b/diagrams/erdiagram_targetdb_latest.pdf differ
diff --git a/docs/tbls/public.fluxstd.md b/docs/tbls/public.fluxstd.md
index 79ca042..bbfcb9e 100644
--- a/docs/tbls/public.fluxstd.md
+++ b/docs/tbls/public.fluxstd.md
@@ -102,9 +102,9 @@
 | fluxstd_pkey | CREATE UNIQUE INDEX fluxstd_pkey ON public.fluxstd USING btree (fluxstd_id) |
 | uq_obj_id_input_catalog_id_version | CREATE UNIQUE INDEX uq_obj_id_input_catalog_id_version ON public.fluxstd USING btree (obj_id, input_catalog_id, version) |
 | ix_fluxstd_version_fluxstdid | CREATE INDEX ix_fluxstd_version_fluxstdid ON public.fluxstd USING btree (version, fluxstd_id) |
-| fluxstd_q3c_ang2ipix_idx | CREATE INDEX fluxstd_q3c_ang2ipix_idx ON public.fluxstd USING btree (q3c_ang2ipix(ra, "dec")) |
-| ix_fluxstd_input_catalog_fluxstdid | CREATE INDEX ix_fluxstd_input_catalog_fluxstdid ON public.fluxstd USING btree (input_catalog_id, fluxstd_id) |
 | ix_fluxstd_version | CREATE INDEX ix_fluxstd_version ON public.fluxstd USING btree (version) |
+| ix_fluxstd_input_catalog_fluxstdid | CREATE INDEX ix_fluxstd_input_catalog_fluxstdid ON public.fluxstd USING btree (input_catalog_id, fluxstd_id) |
+| fluxstd_q3c_ang2ipix_idx | CREATE INDEX fluxstd_q3c_ang2ipix_idx ON public.fluxstd USING btree (q3c_ang2ipix(ra, "dec")) |
 
 ## Relations
 
diff --git a/docs/tbls/public.sky.md b/docs/tbls/public.sky.md
index f4d93bf..3931078 100644
--- a/docs/tbls/public.sky.md
+++ b/docs/tbls/public.sky.md
@@ -35,8 +35,8 @@
 | sky_pkey | CREATE UNIQUE INDEX sky_pkey ON public.sky USING btree (sky_id) |
 | sky_obj_id_input_catalog_id_version_key | CREATE UNIQUE INDEX sky_obj_id_input_catalog_id_version_key ON public.sky USING btree (obj_id, input_catalog_id, version) |
 | sky_q3c_ang2ipix_idx | CREATE INDEX sky_q3c_ang2ipix_idx ON public.sky USING btree (q3c_ang2ipix(ra, "dec")) |
-| ix_sky_version | CREATE INDEX ix_sky_version ON public.sky USING btree (version) |
 | ix_sky_input_catalog_id | CREATE INDEX ix_sky_input_catalog_id ON public.sky USING btree (input_catalog_id) |
+| ix_sky_version | CREATE INDEX ix_sky_version ON public.sky USING btree (version) |
 
 ## Relations
 
diff --git a/src/targetdb/targetdb.py b/src/targetdb/targetdb.py
index 523a4ab..154d888 100644
--- a/src/targetdb/targetdb.py
+++ b/src/targetdb/targetdb.py
@@ -38,9 +38,27 @@ def connect(self):
         # print('connection to {0} started'.format(self.dbinfo))
 
     def close(self):
-        self.session.close()
+        try:
+            self.session.close()
+        finally:
+            # Dispose the engine to release all pooled connections back to the database
+            # server. Without this, SQLAlchemy's connection pool keeps the underlying
+            # TCP sockets open until the engine is garbage-collected, which may never
+            # happen on abnormal process termination.
+            self.engine.dispose()
         # print('connection to {0} closed'.format(self.dbinfo))
 
+    def __enter__(self):
+        """Support usage as a context manager: ``with TargetDB(...) as db:``."""
+        if not hasattr(self, "session"):
+            self.connect()
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        """Ensure close() is called even if an exception occurs inside the block."""
+        self.close()
+        return False  # re-raise any exception
+
     def reset_all(self, full=True):
         #
         # Order of the resetting tables is important