diff --git a/.circleci/config.yml b/.circleci/config.yml
index 87549ac9..bde6e703 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -58,7 +58,11 @@ jobs:
           paths:
             - "venv"
       - run:
+          name: Run Alembic Migrations
           command: ./venv/bin/python ./main.py db upgrade
+      - run:
+          name: Check for Missing Migrations
+          command: ./venv/bin/python ./main.py db check
   api-tests-3-12:
     docker:
       - image: cimg/python:3.12
diff --git a/alembic/env.py b/alembic/env.py
index 751d50af..ac05474b 100644
--- a/alembic/env.py
+++ b/alembic/env.py
@@ -15,9 +15,20 @@ fileConfig(config.config_file_name)
 
 # add your model's MetaData object here
 # for 'autogenerate' support
-# from myapp import mymodel
-# target_metadata = mymodel.Base.metadata
-target_metadata = None
+from wrolpi.common import Base
+# Import all models so they are registered with the Base metadata
+from wrolpi.files.models import FileGroup, Directory  # noqa: F401
+from wrolpi.files.ebooks import EBook  # noqa: F401
+from wrolpi.tags import Tag  # noqa: F401
+from wrolpi.flags import WROLPiFlag  # noqa: F401
+from wrolpi.downloader import Download  # noqa: F401
+from wrolpi.collections.models import Collection, CollectionItem  # noqa: F401
+from modules.videos.models import Video, Channel  # noqa: F401
+from modules.archive.models import Archive  # noqa: F401
+from modules.zim.models import Zim, TagZimEntry, ZimSubscription  # noqa: F401
+from modules.map.models import MapFile  # noqa: F401
+from modules.inventory.models import Item, Inventory  # noqa: F401
+target_metadata = Base.metadata
 
 
 # other values from the config, defined by the needs of env.py,
diff --git a/alembic/versions/f38cfe4b5cb2_collections_feature.py b/alembic/versions/f38cfe4b5cb2_collections_feature.py
new file mode 100644
index 00000000..39d0ed9a
--- /dev/null
+++ b/alembic/versions/f38cfe4b5cb2_collections_feature.py
@@ -0,0 +1,68 @@
+"""collections feature
+
+Revision ID: f38cfe4b5cb2
+Revises: add_unique_collection_name_kind
+Create Date: 2025-11-29 16:51:34.222412
+
+"""
+import sqlalchemy as sa
+from alembic import op
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = 'f38cfe4b5cb2'
+down_revision = 'add_unique_collection_name_kind'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column('archive', 'collection_id',
+               existing_type=sa.INTEGER(),
+               nullable=True)
+    op.alter_column('file_group', 'mimetype',
+               existing_type=sa.TEXT(),
+               nullable=True)
+    op.alter_column('tag_file', 'tag_id',
+               existing_type=sa.INTEGER(),
+               nullable=False)
+    op.alter_column('tag_file', 'file_group_id',
+               existing_type=sa.BIGINT(),
+               nullable=False)
+    op.alter_column('tag_zim', 'tag_id',
+               existing_type=sa.INTEGER(),
+               nullable=False)
+    op.alter_column('tag_zim', 'zim_id',
+               existing_type=sa.INTEGER(),
+               nullable=False)
+    op.drop_index('video_upload_date_idx', table_name='video')
+    op.drop_column('video', 'duration')
+    op.drop_column('video', 'upload_date')
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('video', sa.Column('upload_date', postgresql.TIMESTAMP(timezone=True), autoincrement=False, nullable=True))
+    op.add_column('video', sa.Column('duration', sa.INTEGER(), autoincrement=False, nullable=True))
+    op.create_index('video_upload_date_idx', 'video', ['upload_date'], unique=False)
+    op.alter_column('tag_zim', 'zim_id',
+               existing_type=sa.INTEGER(),
+               nullable=True)
+    op.alter_column('tag_zim', 'tag_id',
+               existing_type=sa.INTEGER(),
+               nullable=True)
+    op.alter_column('tag_file', 'file_group_id',
+               existing_type=sa.BIGINT(),
+               nullable=True)
+    op.alter_column('tag_file', 'tag_id',
+               existing_type=sa.INTEGER(),
+               nullable=True)
+    op.alter_column('archive', 'collection_id',
+               existing_type=sa.INTEGER(),
+               nullable=False)
+    op.alter_column('file_group', 'mimetype',
+               existing_type=sa.TEXT(),
+               nullable=False)
+    # ### end Alembic commands ###
diff --git a/main.py b/main.py
index 28e13bab..8abff9af 100755
--- a/main.py
+++ b/main.py
@@ -32,7 +32,7 @@ logger = logger.getChild('wrolpi-main')
 
 def db_main(args):
     """
-    Handle database migrations.  This uses Alembic, supported commands are "upgrade" and "downgrade".
+    Handle database migrations.  This uses Alembic, supported commands are "upgrade", "downgrade", and "check".
     """
     from alembic.config import Config
     from alembic import command
@@ -48,6 +48,11 @@ def db_main(args):
         command.upgrade(config, 'head')
     elif args.command == 'downgrade':
         command.downgrade(config, '-1')
+    elif args.command == 'check':
+        command.check(config)
+    elif args.command == 'revision':
+        message = getattr(args, 'message', None) or 'auto migration'
+        command.revision(config, message=message, autogenerate=True)
     else:
         print(f'Unknown DB command: {args.command}')
         return 2
@@ -100,7 +105,8 @@ def main():
 
     # DB Parser for running Alembic migrations
     db_parser = sub_commands.add_parser('db')
-    db_parser.add_argument('command', help='Supported commands: upgrade, downgrade')
+    db_parser.add_argument('command', help='Supported commands: upgrade, downgrade, check, revision')
+    db_parser.add_argument('-m', '--message', help='Migration message (for revision command)')
 
     args = parser.parse_args()
 
diff --git a/modules/archive/__init__.py b/modules/archive/__init__.py
index b2702595..974495ed 100644
--- a/modules/archive/__init__.py
+++ b/modules/archive/__init__.py
@@ -190,6 +190,7 @@ def model_archive(file_group: FileGroup, session: Session = None) -> Archive:
 
             # Set collection_id BEFORE adding to session to avoid autoflush constraint violation
             from modules.archive.lib import get_or_create_domain_collection
+
             if file_group.url:
                 # URL is already set on the FileGroup
                 collection = get_or_create_domain_collection(session, file_group.url)
@@ -202,12 +203,8 @@ def model_archive(file_group: FileGroup, session: Session = None) -> Archive:
                     collection = get_or_create_domain_collection(session, url)
                     archive.collection_id = collection.id if collection else None
                 except (RuntimeError, ValueError) as e:
-                    # Could not extract URL from singlefile
-                    if not PYTEST:
-                        # In production, archives must have a URL/collection
-                        raise InvalidArchive(f'Archive has no URL and could not extract from singlefile: {e}') from e
-                    # In tests, allow archives without collections (factory will set it later)
-                    logger.debug(f'Could not extract URL from singlefile (test mode): {e}')
+                    # Could not extract URL from singlefile - archive will have no collection
+                    logger.debug(f'Could not extract URL from singlefile: {e}')
                     archive.collection_id = None
 
             session.add(archive)
diff --git a/modules/inventory/models.py b/modules/inventory/models.py
index c8289204..6b481d9b 100644
--- a/modules/inventory/models.py
+++ b/modules/inventory/models.py
@@ -23,7 +23,7 @@ class Item(Base, ModelHelper):
     subcategory = Column(String)
     unit = Column(String)
 
-    inventory_id = Column(Integer, ForeignKey('inventory.id'))
+    inventory_id = Column(Integer, ForeignKey('inventory.id', ondelete='CASCADE'))
     inventory = relationship('Inventory', primaryjoin="Item.inventory_id==Inventory.id", back_populates='items')
 
     def __repr__(self):
@@ -35,7 +35,7 @@ class Inventory(Base, ModelHelper):
     __tablename__ = 'inventory'
     id = Column(Integer, primary_key=True)
 
-    name = Column(String, unique=True)
+    name = Column(String, unique=True, nullable=False)
     viewed_at = Column(TZDateTime)
     created_at = Column(TZDateTime, default=now)
     deleted_at = Column(TZDateTime)
@@ -61,6 +61,3 @@ class Inventory(Base, ModelHelper):
         return session.query(Inventory).filter_by(name=name).one()
 
 
-class InventoriesVersion(Base, ModelHelper):
-    __tablename__ = 'inventories_version'
-    version = Column(Integer, primary_key=True)
diff --git a/modules/map/models.py b/modules/map/models.py
index 356983b2..9462c299 100644
--- a/modules/map/models.py
+++ b/modules/map/models.py
@@ -10,8 +10,8 @@ class MapFile(Base, ModelHelper):
     __tablename__ = 'map_file'
     id = Column(Integer, primary_key=True)
 
-    path = Column(MediaPathType, unique=True, nullable=False)
-    imported = Column(Boolean, default=False, nullable=False)
+    path = Column(MediaPathType, nullable=False)
+    imported = Column(Boolean, default=False)
     size = Column(BigInteger)
 
     def __repr__(self):
diff --git a/modules/videos/models.py b/modules/videos/models.py
index a2a197fc..b4a25b5c 100644
--- a/modules/videos/models.py
+++ b/modules/videos/models.py
@@ -2,7 +2,7 @@ import json
 import pathlib
 from typing import Optional, Dict, List
 
-from sqlalchemy import Column, Integer, String, Boolean, JSON, Date, ForeignKey, BigInteger
+from sqlalchemy import Column, Integer, String, Boolean, JSON, Date, ForeignKey, BigInteger, Index, text
 from sqlalchemy.orm import relationship, Session, deferred
 from sqlalchemy.orm.collections import InstrumentedList
 
@@ -28,6 +28,11 @@ __all__ = ['Video', 'Channel']
 
 class Video(ModelHelper, Base):
     __tablename__ = 'video'
+    __table_args__ = (
+        Index('video_channel_id_idx', 'channel_id'),
+        Index('video_source_id_idx', 'source_id'),
+        Index('video_view_count_idx', 'view_count'),
+    )
     id = Column(Integer, primary_key=True)
 
     source_id = Column(String)  # The id from yt-dlp
@@ -530,9 +535,16 @@ class Video(ModelHelper, Base):
 
 class Channel(ModelHelper, Base):
     __tablename__ = 'channel'
+    __table_args__ = (
+        Index('channel_minimum_frequency_idx', 'minimum_frequency'),
+        Index('channel_source_id', 'source_id'),
+        Index('channel_total_size_idx', 'total_size'),
+        Index('channel_video_count_idx', 'video_count'),
+        Index('channel_url_key', 'url', unique=True, postgresql_where=text('url IS NOT NULL')),
+    )
     id = Column(Integer, primary_key=True)
     # name and directory are stored in Collection, accessed via properties
-    url = Column(String, unique=True)  # will only be downloaded if related Download exists.
+    url = Column(String)  # will only be downloaded if related Download exists. Partial unique index on non-NULL values.
     generate_posters = Column(Boolean, default=False)  # generating posters may delete files, and can be slow.
     calculate_duration = Column(Boolean, default=True)  # use ffmpeg to extract duration (slower than info json).
     download_missing_data = Column(Boolean, default=True)  # fetch missing data like `source_id` and video comments.
@@ -540,8 +552,8 @@ class Channel(ModelHelper, Base):
     refreshed = Column(Boolean, default=False)  # The files in the Channel have been refreshed.
 
     # Columns updated by triggers
-    video_count = Column(Integer, default=0)  # update_channel_video_count
-    total_size = Column(Integer, default=0)  # update_channel_size
+    video_count = Column(Integer, default=0, nullable=False)  # update_channel_video_count
+    total_size = Column(BigInteger, default=0, nullable=False)  # update_channel_size
     minimum_frequency = Column(Integer)  # update_channel_minimum_frequency
 
     info_json = deferred(Column(JSON))
diff --git a/modules/zim/models.py b/modules/zim/models.py
index 80d74b2f..e1126ea2 100644
--- a/modules/zim/models.py
+++ b/modules/zim/models.py
@@ -6,7 +6,7 @@ from datetime import datetime
 from typing import List, Tuple, OrderedDict as OrderedDictType, Dict, Optional, Set
 
 from libzim import Archive, Searcher, Query, Entry, SuggestionSearcher
-from sqlalchemy import Column, Integer, BigInteger, ForeignKey, Text, tuple_, Boolean
+from sqlalchemy import Column, Integer, BigInteger, ForeignKey, Text, tuple_, Boolean, UniqueConstraint
 from sqlalchemy.orm import relationship, Session
 from sqlalchemy.orm.exc import NoResultFound  # noqa
 
@@ -67,12 +67,15 @@ class Zim(Base, ModelHelper):
     """
 
     __tablename__ = 'zim'
+    __table_args__ = (
+        UniqueConstraint('path', name='zim_path_key'),
+    )
     id = Column(Integer, primary_key=True)
     path: pathlib.Path = Column(MediaPathType, nullable=False)
 
-    file_group_id = Column(BigInteger, ForeignKey('file_group.id', ondelete='CASCADE'), unique=True, nullable=False)
+    file_group_id = Column(BigInteger, ForeignKey('file_group.id', ondelete='CASCADE'), nullable=False)
     file_group: FileGroup = relationship('FileGroup')
-    auto_search = Column(Boolean, nullable=False, default=True)
+    auto_search = Column(Boolean, default=True)
 
     def __repr__(self):
         return f'<Zim id={self.id} file_group_id={self.file_group_id} path={self.path}>'
@@ -353,8 +356,11 @@ class Zims:
 
 class TagZimEntry(Base):
     __tablename__ = 'tag_zim'
+    __table_args__ = (
+        UniqueConstraint('tag_id', 'zim_id', 'zim_entry', name='tag_zim_tag_id_zim_id_zim_entry_key'),
+    )
 
-    tag_id = Column(Integer, ForeignKey('tag.id', ondelete='CASCADE'), primary_key=True)
+    tag_id = Column(Integer, ForeignKey('tag.id'), primary_key=True)
     tag: Tag = relationship('Tag')
     zim_id = Column(Integer, ForeignKey('zim.id', ondelete='CASCADE'), primary_key=True)
     zim: Zim = relationship('Zim')
diff --git a/modules/zim/test/test_lib.py b/modules/zim/test/test_lib.py
index f6a0b1ca..4814262f 100644
--- a/modules/zim/test/test_lib.py
+++ b/modules/zim/test/test_lib.py
@@ -161,10 +161,9 @@ async def test_zim_tags_config(async_client, test_session, test_directory, test_
         ['Tag1', test_zim.path.name, 'two', '2000-01-01T00:00:00.000001+00:00'],
     ]
 
-    # Delete all Tags so they are recreated.
-    test_session.query(tags.Tag).delete()
-    # Delete all TagFileEntry(s), import them again.
+    # Delete all TagZimEntry(s) first (due to FK constraint), then Tags so they are recreated.
     test_session.query(TagZimEntry).delete()
+    test_session.query(tags.Tag).delete()
     test_session.commit()
 
     tags.import_tags_config()
diff --git a/wrolpi/collections/models.py b/wrolpi/collections/models.py
index 31e17a51..20c6bdab 100644
--- a/wrolpi/collections/models.py
+++ b/wrolpi/collections/models.py
@@ -1,7 +1,7 @@
 import pathlib
 from typing import Optional, List
 
-from sqlalchemy import Column, Integer, String, ForeignKey, Text, DateTime, Index, UniqueConstraint, func
+from sqlalchemy import Column, Integer, String, ForeignKey, Text, DateTime, Index, UniqueConstraint, func, BigInteger
 from sqlalchemy.orm import relationship, Session
 from sqlalchemy.orm.collections import InstrumentedList
 
@@ -67,6 +67,8 @@ class Collection(ModelHelper, Base):
         UniqueConstraint('directory', name='uq_collection_directory'),
         UniqueConstraint('name', 'kind', name='uq_collection_name_kind'),
         Index('idx_collection_kind', 'kind'),
+        Index('idx_collection_item_count', 'item_count'),
+        Index('idx_collection_total_size', 'total_size'),
     )
 
     id = Column(Integer, primary_key=True)
@@ -80,14 +82,14 @@ class Collection(ModelHelper, Base):
     directory: Optional[pathlib.Path] = Column(MediaPathType, nullable=True)
 
     # Optional tag relationship (similar to Channel)
-    tag_id = Column(Integer, ForeignKey('tag.id', ondelete='CASCADE'))
+    tag_id = Column(Integer, ForeignKey('tag.id'))
     tag = relationship('Tag', primaryjoin='Collection.tag_id==Tag.id')
 
-    created_date = Column(DateTime, server_default=func.now())
+    created_date = Column(DateTime, server_default=func.now(), nullable=False)
 
     # Columns updated by triggers (similar to Channel)
-    item_count = Column(Integer, default=0)
-    total_size = Column(Integer, default=0)
+    item_count = Column(Integer, default=0, nullable=False)
+    total_size = Column(BigInteger, default=0, nullable=False)
 
     # Relationship to items (ordered)
     items: InstrumentedList = relationship(
@@ -790,7 +792,7 @@ class CollectionItem(ModelHelper, Base):
     position = Column(Integer, nullable=False, default=0)
 
     # When this item was added
-    added_date = Column(DateTime, server_default=func.now())
+    added_date = Column(DateTime, server_default=func.now(), nullable=False)
 
     # Relationships
     collection = relationship('Collection', back_populates='items')
@@ -798,8 +800,10 @@ class CollectionItem(ModelHelper, Base):
 
     # Indexes for performance
     __table_args__ = (
+        Index('idx_collection_item_collection_id', 'collection_id'),
         Index('idx_collection_item_collection_position', 'collection_id', 'position'),
-        Index('idx_collection_item_file_group', 'file_group_id'),
+        Index('idx_collection_item_file_group_id', 'file_group_id'),
+        Index('idx_collection_item_position', 'position'),
         UniqueConstraint('collection_id', 'file_group_id', name='uq_collection_file_group'),
     )
 
diff --git a/wrolpi/downloader.py b/wrolpi/downloader.py
index 73f3957f..f58f422d 100644
--- a/wrolpi/downloader.py
+++ b/wrolpi/downloader.py
@@ -20,7 +20,7 @@ from urllib.parse import urlparse
 import feedparser
 import pytz
 from feedparser import FeedParserDict
-from sqlalchemy import Column, Integer, String, Text, ForeignKey, ARRAY
+from sqlalchemy import Column, Integer, String, Text, ForeignKey, ARRAY, Index
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Session, relationship
 from sqlalchemy.sql import Delete
@@ -100,6 +100,9 @@ class DownloadStatus(str, Enum):
 class Download(ModelHelper, Base):  # noqa
     """Model that is used to schedule downloads."""
     __tablename__ = 'download'  # noqa
+    __table_args__ = (
+        Index('idx_download_collection_id', 'collection_id'),
+    )
     id = Column(Integer, primary_key=True)
     url = Column(String, nullable=False, unique=True)
 
diff --git a/wrolpi/files/ebooks.py b/wrolpi/files/ebooks.py
index 6d9a2b23..43688bf7 100644
--- a/wrolpi/files/ebooks.py
+++ b/wrolpi/files/ebooks.py
@@ -4,7 +4,7 @@ import logging
 import pathlib
 from typing import List, Optional, Tuple
 
-from sqlalchemy import Column, Integer, BigInteger, ForeignKey, or_, and_
+from sqlalchemy import Column, Integer, BigInteger, ForeignKey, or_, and_, Index
 from sqlalchemy.orm import relationship, Session
 
 from wrolpi.common import ModelHelper, Base, register_modeler, get_html_soup
@@ -150,6 +150,9 @@ def discover_calibre_cover(ebook_path: pathlib.Path):
 
 class EBook(ModelHelper, Base):
     __tablename__ = 'ebook'
+    __table_args__ = (
+        Index('ebook_size_idx', 'size'),
+    )
     id = Column(Integer, primary_key=True)
     size: int = Column(Integer)
 
diff --git a/wrolpi/files/models.py b/wrolpi/files/models.py
index 7eb2fda2..533aeb81 100644
--- a/wrolpi/files/models.py
+++ b/wrolpi/files/models.py
@@ -6,7 +6,7 @@ from datetime import datetime
 from functools import singledispatchmethod
 from typing import List, Type, Optional, Iterable
 
-from sqlalchemy import Column, String, Computed, BigInteger, Boolean, event
+from sqlalchemy import Column, String, Computed, BigInteger, Boolean, event, Index
 from sqlalchemy import types
 from sqlalchemy.orm import deferred, relationship, Session
 
@@ -66,15 +66,30 @@ class FancyJSON(types.TypeDecorator):
 
 class FileGroup(ModelHelper, Base):
     __tablename__ = 'file_group'
+    __table_args__ = (
+        Index('file_group_author_idx', 'author'),
+        Index('file_group_download_datetime_idx', 'download_datetime'),
+        Index('file_group_effective_datetime_idx', 'effective_datetime'),
+        Index('file_group_length_idx', 'length'),
+        Index('file_group_mimetype_idx', 'mimetype'),
+        Index('file_group_model_idx', 'model'),
+        Index('file_group_modification_datetime_idx', 'modification_datetime'),
+        Index('file_group_published_datetime_idx', 'published_datetime'),
+        Index('file_group_published_modified_datetime_idx', 'published_modified_datetime'),
+        Index('file_group_size_ix', 'size'),
+        Index('file_group_textsearch_idx', 'textsearch'),
+        Index('file_group_url_idx', 'url'),
+        Index('file_group_viewed_idx', 'viewed'),
+    )
     id: int = Column(BigInteger, primary_key=True)
 
     author = Column(String)  # name of the author, maybe even a URL
     censored = Column(Boolean)  # the file is no longer available for download
     data = Column(FancyJSON)  # populated by the modeler
     download_datetime = Column(TZDateTime)  # the date WROLPi downloaded this file.
-    files = Column(FancyJSON, nullable=False)  # populated during discovery
+    files = Column(FancyJSON)  # populated during discovery
     idempotency = Column(TZDateTime)  # used to track which files need to be deleted during refresh
-    indexed = Column(Boolean, default=lambda: False, nullable=False)  # wrolpi.files.lib.apply_indexers
+    indexed = Column(Boolean, default=lambda: False)  # wrolpi.files.lib.apply_indexers
     length = Column(BigInteger)  # video duration, article words, etc.
     mimetype = Column(String)  # wrolpi.files.lib.get_mimetype
     model = Column(String)  # "video", "archive", "ebook", etc.
@@ -550,6 +565,9 @@ def update_effective_datetime(mapper, connection, target):
 class Directory(ModelHelper, Base):
     """A representation of a file directory in the media directory."""
     __tablename__ = 'directory'
+    __table_args__ = (
+        Index('directory_name_idx', 'name'),
+    )
 
     path: pathlib.Path = Column(MediaPathType, primary_key=True)
     name: str = Column(String, nullable=False)
diff --git a/wrolpi/tags.py b/wrolpi/tags.py
index 36c9d7c4..08a47e12 100644
--- a/wrolpi/tags.py
+++ b/wrolpi/tags.py
@@ -6,7 +6,7 @@ from typing import List, Dict, Tuple, Optional
 
 import cachetools
 from cachetools.keys import hashkey
-from sqlalchemy import Column, Integer, String, ForeignKey, BigInteger, event
+from sqlalchemy import Column, Integer, String, ForeignKey, BigInteger, event, UniqueConstraint
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.orm import relationship, Session
 
@@ -30,9 +30,12 @@ def get_tags_directory() -> pathlib.Path:
 
 class TagFile(ModelHelper, Base):
     __tablename__ = 'tag_file'
+    __table_args__ = (
+        UniqueConstraint('tag_id', 'file_group_id', name='tag_file_tag_id_file_group_id_key'),
+    )
     created_at: datetime = Column(TZDateTime, default=dates.now)
 
-    tag_id = Column(Integer, ForeignKey('tag.id', ondelete='CASCADE'), primary_key=True)
+    tag_id = Column(Integer, ForeignKey('tag.id'), primary_key=True)
     tag = relationship('Tag', back_populates='tag_files')
     file_group_id = Column(BigInteger, ForeignKey('file_group.id', ondelete='CASCADE'), primary_key=True)
     file_group = relationship('FileGroup', back_populates='tag_files')