diff --git a/server/szurubooru/db/__init__.py b/server/szurubooru/db/__init__.py
index 0c65170e..20073dfd 100644
--- a/server/szurubooru/db/__init__.py
+++ b/server/szurubooru/db/__init__.py
@@ -1,3 +1,4 @@
 from szurubooru.db.base import Base
 from szurubooru.db.user import User
 from szurubooru.db.tag import Tag, TagName, TagSuggestion, TagImplication
+from szurubooru.db.post import Post, PostTag, PostRelation
diff --git a/server/szurubooru/db/post.py b/server/szurubooru/db/post.py
new file mode 100644
index 00000000..da443381
--- /dev/null
+++ b/server/szurubooru/db/post.py
@@ -0,0 +1,82 @@
+from sqlalchemy import Column, Integer, DateTime, String, ForeignKey
+from sqlalchemy.orm import relationship, column_property
+from sqlalchemy.sql.expression import func, select
+from szurubooru.db.base import Base
+
+class PostRelation(Base):
+    __tablename__ = 'post_relation'
+
+    parent_id = Column('parent_id', Integer, ForeignKey('post.id'), primary_key=True)
+    child_id = Column('child_id', Integer, ForeignKey('post.id'), primary_key=True)
+
+    def __init__(self, parent_id, child_id):
+        self.parent_id = parent_id
+        self.child_id = child_id
+
+class PostTag(Base):
+    __tablename__ = 'post_tag'
+
+    post_id = Column('post_id', Integer, ForeignKey('post.id'), primary_key=True)
+    tag_id = Column('tag_id', Integer, ForeignKey('tag.id'), primary_key=True)
+
+    def __init__(self, tag_id, post_id):
+        self.tag_id = tag_id
+        self.post_id = post_id
+
+class Post(Base):
+    __tablename__ = 'post'
+
+    SAFETY_SAFE = 'safe'
+    SAFETY_SKETCHY = 'sketchy'
+    SAFETY_UNSAFE = 'unsafe'
+    TYPE_IMAGE = 'anim'
+    TYPE_ANIMATION = 'anim'
+    TYPE_FLASH = 'flash'
+    TYPE_VIDEO = 'video'
+    TYPE_YOUTUBE = 'youtube'
+    FLAG_LOOP_VIDEO = 1
+
+    post_id = Column('id', Integer, primary_key=True)
+    user_id = Column('user_id', Integer, ForeignKey('user.id'))
+    creation_time = Column('creation_time', DateTime, nullable=False)
+    last_edit_time = Column('last_edit_time', DateTime)
+    safety = Column('safety', String(32), nullable=False)
+    type = Column('type', String(32), nullable=False)
+    checksum = Column('checksum', String(64), nullable=False)
+    source = Column('source', String(200))
+    file_size = Column('file_size', Integer)
+    image_width = Column('image_width', Integer)
+    image_height = Column('image_height', Integer)
+    flags = Column('flags', Integer, nullable=False, default=0)
+
+    user = relationship('User')
+    tags = relationship('Tag', backref='posts', secondary='post_tag')
+    relations = relationship(
+        'Post',
+        secondary='post_relation',
+        primaryjoin=post_id == PostRelation.parent_id,
+        secondaryjoin=post_id == PostRelation.child_id)
+
+    tag_count = column_property(
+        select(
+            [func.count('1')],
+            PostTag.post_id == post_id
+        ) \
+        .correlate('Post') \
+        .label('tag_count')
+    )
+
+    # TODO: wire these
+    fav_count = Column('auto_fav_count', Integer, nullable=False, default=0)
+    score = Column('auto_score', Integer, nullable=False, default=0)
+    feature_count = Column('auto_feature_count', Integer, nullable=False, default=0)
+    comment_count = Column('auto_comment_count', Integer, nullable=False, default=0)
+    note_count = Column('auto_note_count', Integer, nullable=False, default=0)
+    last_fav_time = Column(
+        'auto_fav_time', Integer, nullable=False, default=0)
+    last_feature_time = Column(
+        'auto_feature_time', Integer, nullable=False, default=0)
+    last_comment_edit_time = Column(
+        'auto_comment_creation_time', Integer, nullable=False, default=0)
+    last_comment_creation_time = Column(
+        'auto_comment_edit_time', Integer, nullable=False, default=0)
diff --git a/server/szurubooru/db/tag.py b/server/szurubooru/db/tag.py
index dbdfed90..3254ba41 100644
--- a/server/szurubooru/db/tag.py
+++ b/server/szurubooru/db/tag.py
@@ -1,6 +1,8 @@
 from sqlalchemy import Column, Integer, DateTime, String, ForeignKey
-from sqlalchemy.orm import relationship
+from sqlalchemy.orm import relationship, column_property
+from sqlalchemy.sql.expression import func, select
 from szurubooru.db.base import Base
+from szurubooru.db.post import PostTag
 
 class TagSuggestion(Base):
     __tablename__ = 'tag_suggestion'
@@ -52,5 +54,11 @@ class Tag(Base):
         primaryjoin=tag_id == TagImplication.parent_id,
         secondaryjoin=tag_id == TagImplication.child_id)
 
-    # TODO: wire this
-    post_count = Column('auto_post_count', Integer, nullable=False, default=0)
+    post_count = column_property(
+        select(
+            [func.count('Post.post_id')],
+            PostTag.tag_id == tag_id
+        ) \
+        .correlate('Tag') \
+        .label('post_count')
+    )
diff --git a/server/szurubooru/migrations/versions/00cb3a2734db_create_tags_tables.py b/server/szurubooru/migrations/versions/00cb3a2734db_create_tags_tables.py
index fe85ade7..ba20230c 100644
--- a/server/szurubooru/migrations/versions/00cb3a2734db_create_tags_tables.py
+++ b/server/szurubooru/migrations/versions/00cb3a2734db_create_tags_tables.py
@@ -20,7 +20,6 @@ def upgrade():
         sa.Column('category', sa.String(length=32), nullable=False),
         sa.Column('creation_time', sa.DateTime(), nullable=False),
         sa.Column('last_edit_time', sa.DateTime(), nullable=True),
-        sa.Column('auto_post_count', sa.Integer(), nullable=False),
         sa.PrimaryKeyConstraint('id'))
 
     op.create_table(
diff --git a/server/szurubooru/search/tag_search_config.py b/server/szurubooru/search/tag_search_config.py
index 080538fa..434bf146 100644
--- a/server/szurubooru/search/tag_search_config.py
+++ b/server/szurubooru/search/tag_search_config.py
@@ -4,11 +4,7 @@ from szurubooru import db
 from szurubooru.search.base_search_config import BaseSearchConfig
 
 class TagSearchConfig(BaseSearchConfig):
-    def __init__(self):
-        self._session = None
-
     def create_query(self, session):
-        self._session = session
         return session.query(db.Tag)
 
     def finalize_query(self, query):
@@ -65,7 +61,7 @@ class TagSearchConfig(BaseSearchConfig):
         str_filter = self._create_str_filter(db.TagName.name)
         return query.filter(
             db.Tag.tag_id.in_(
-                str_filter(self._session.query(db.TagName.tag_id), criterion)))
+                str_filter(query.session.query(db.TagName.tag_id), criterion)))
 
     def _suggestion_count_filter(self, query, criterion):
         return query.filter(
diff --git a/server/szurubooru/tests/api/test_tag_deleting.py b/server/szurubooru/tests/api/test_tag_deleting.py
index 852cce4d..a895bec5 100644
--- a/server/szurubooru/tests/api/test_tag_deleting.py
+++ b/server/szurubooru/tests/api/test_tag_deleting.py
@@ -48,10 +48,11 @@ def test_removing_tags_without_privileges(test_ctx):
             'tag')
     assert test_ctx.session.query(db.Tag).count() == 1
 
-def test_removing_tags_with_usages(test_ctx):
+def test_removing_tags_with_usages(test_ctx, post_factory):
     tag = test_ctx.tag_factory(names=['tag'])
-    tag.post_count = 5
-    test_ctx.session.add(tag)
+    post = post_factory()
+    post.tags.append(tag)
+    test_ctx.session.add_all([tag, post])
     test_ctx.session.commit()
     with pytest.raises(tags.TagIsInUseError):
         test_ctx.api.delete(
diff --git a/server/szurubooru/tests/conftest.py b/server/szurubooru/tests/conftest.py
index e0d6785e..239f5b69 100644
--- a/server/szurubooru/tests/conftest.py
+++ b/server/szurubooru/tests/conftest.py
@@ -71,3 +71,18 @@ def tag_factory():
         tag.creation_time = datetime.datetime(1996, 1, 1)
         return tag
     return factory
+
+@pytest.fixture
+def post_factory():
+    def factory(
+            safety=db.Post.SAFETY_SAFE,
+            type=db.Post.TYPE_IMAGE,
+            checksum='...'):
+        post = db.Post()
+        post.safety = safety
+        post.type = type
+        post.checksum = checksum
+        post.flags = 0
+        post.creation_time = datetime.datetime(1996, 1, 1)
+        return post
+    return factory
diff --git a/server/szurubooru/tests/db/test_post.py b/server/szurubooru/tests/db/test_post.py
new file mode 100644
index 00000000..1415f2b9
--- /dev/null
+++ b/server/szurubooru/tests/db/test_post.py
@@ -0,0 +1,91 @@
+from datetime import datetime
+from szurubooru import db
+
+def test_saving_post(session, post_factory, user_factory, tag_factory):
+    user = user_factory()
+    tag1 = tag_factory()
+    tag2 = tag_factory()
+    related_post1 = post_factory()
+    related_post2 = post_factory()
+    post = db.Post()
+    post.safety = 'safety'
+    post.type = 'type'
+    post.checksum = 'deadbeef'
+    post.creation_time = datetime(1997, 1, 1)
+    post.last_edit_time = datetime(1998, 1, 1)
+    session.add_all([user, tag1, tag2, related_post1, related_post2, post])
+
+    post.user = user
+    post.tags.append(tag1)
+    post.tags.append(tag2)
+    post.relations.append(related_post1)
+    post.relations.append(related_post2)
+    session.commit()
+
+    post = session.query(db.Post).filter(db.Post.post_id == post.post_id).one()
+    assert not session.dirty
+    assert post.user.user_id is not None
+    assert post.safety == 'safety'
+    assert post.type == 'type'
+    assert post.checksum == 'deadbeef'
+    assert post.creation_time == datetime(1997, 1, 1)
+    assert post.last_edit_time == datetime(1998, 1, 1)
+    assert len(post.relations) == 2
+
+def test_cascade_deletions(session, post_factory, user_factory, tag_factory):
+    user = user_factory()
+    tag1 = tag_factory()
+    tag2 = tag_factory()
+    related_post1 = post_factory()
+    related_post2 = post_factory()
+    post = post_factory()
+    session.add_all([user, tag1, tag2, post, related_post1, related_post2])
+    session.flush()
+
+    post.user = user
+    post.tags.append(tag1)
+    post.tags.append(tag2)
+    post.relations.append(related_post1)
+    post.relations.append(related_post2)
+    session.flush()
+
+    assert not session.dirty
+    assert post.user.user_id is not None
+    assert len(post.relations) == 2
+    assert session.query(db.User).count() == 1
+    assert session.query(db.Tag).count() == 2
+    assert session.query(db.Post).count() == 3
+    assert session.query(db.PostTag).count() == 2
+    assert session.query(db.PostRelation).count() == 2
+
+    session.delete(post)
+    session.commit()
+
+    assert not session.dirty
+    assert session.query(db.User).count() == 1
+    assert session.query(db.Tag).count() == 2
+    assert session.query(db.Post).count() == 2
+    assert session.query(db.PostTag).count() == 0
+    assert session.query(db.PostRelation).count() == 0
+
+def test_tracking_tag_count(session, post_factory, tag_factory):
+    post = post_factory()
+    tag1 = tag_factory()
+    tag2 = tag_factory()
+    session.add_all([tag1, tag2, post])
+    session.flush()
+    post.tags.append(tag1)
+    post.tags.append(tag2)
+    session.commit()
+    assert len(post.tags) == 2
+    assert post.tag_count == 2
+    session.delete(tag1)
+    session.commit()
+    session.refresh(post)
+    assert len(post.tags) == 1
+    assert post.tag_count == 1
+    session.delete(tag2)
+    session.commit()
+    session.refresh(post)
+    assert len(post.tags) == 0
+    assert post.tag_count == 0
diff --git a/server/szurubooru/tests/db/test_tag.py b/server/szurubooru/tests/db/test_tag.py
index 3c40b880..dfbafbac 100644
--- a/server/szurubooru/tests/db/test_tag.py
+++ b/server/szurubooru/tests/db/test_tag.py
@@ -13,7 +13,6 @@ def test_saving_tag(session, tag_factory):
     tag.category = 'category'
     tag.creation_time = datetime(1997, 1, 1)
     tag.last_edit_time = datetime(1998, 1, 1)
-    tag.post_count = 1
     session.add_all([
         tag, suggested_tag1, suggested_tag2, implied_tag1, implied_tag2])
     session.commit()
@@ -37,7 +36,6 @@ def test_saving_tag(session, tag_factory):
     assert tag.category == 'category'
     assert tag.creation_time == datetime(1997, 1, 1)
     assert tag.last_edit_time == datetime(1998, 1, 1)
-    assert tag.post_count == 1
     assert [relation.names[0].name for relation in tag.suggestions] \
         == ['suggested1', 'suggested2']
     assert [relation.names[0].name for relation in tag.implications] \
@@ -77,3 +75,24 @@ def test_cascade_deletions(session, tag_factory):
     assert session.query(db.TagName).count() == 4
     assert session.query(db.TagImplication).count() == 0
     assert session.query(db.TagSuggestion).count() == 0
+
+def test_tracking_post_count(session, post_factory, tag_factory):
+    tag = tag_factory()
+    post1 = post_factory()
+    post2 = post_factory()
+    session.add_all([tag, post1, post2])
+    session.flush()
+    post1.tags.append(tag)
+    post2.tags.append(tag)
+    session.commit()
+    assert len(post1.tags) == 1
+    assert len(post2.tags) == 1
+    assert tag.post_count == 2
+    session.delete(post1)
+    session.commit()
+    session.refresh(tag)
+    assert tag.post_count == 1
+    session.delete(post2)
+    session.commit()
+    session.refresh(tag)
+    assert tag.post_count == 0