feat: Add alembic migrations and database foreign key indexes

backend/alembic.ini

@@ -0,0 +1,149 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts.
+# this is typically a path given in POSIX (e.g. forward slashes)
+# format, relative to the token %(here)s which refers to the location of this
+# ini file
+script_location = %(here)s/alembic
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+# Or organize into date-based subdirectories (requires recursive_version_locations = true)
+# file_template = %%(year)d/%%(month).2d/%%(day).2d_%%(hour).2d%%(minute).2d_%%(second).2d_%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.  for multiple paths, the path separator
+# is defined by "path_separator" below.
+prepend_sys_path = .
+
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the tzdata library which can be installed by adding
+# `alembic[tz]` to the pip requirements.
+# string value is passed to ZoneInfo()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to <script_location>/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "path_separator"
+# below.
+# version_locations = %(here)s/bar:%(here)s/bat:%(here)s/alembic/versions
+
+# path_separator; This indicates what character is used to split lists of file
+# paths, including version_locations and prepend_sys_path within configparser
+# files such as alembic.ini.
+# The default rendered in new alembic.ini files is "os", which uses os.pathsep
+# to provide os-dependent path splitting.
+#
+# Note that in order to support legacy alembic.ini files, this default does NOT
+# take place if path_separator is not present in alembic.ini.  If this
+# option is omitted entirely, fallback logic is as follows:
+#
+# 1. Parsing of the version_locations option falls back to using the legacy
+#    "version_path_separator" key, which if absent then falls back to the legacy
+#    behavior of splitting on spaces and/or commas.
+# 2. Parsing of the prepend_sys_path option falls back to the legacy
+#    behavior of splitting on spaces, commas, or colons.
+#
+# Valid values for path_separator are:
+#
+# path_separator = :
+# path_separator = ;
+# path_separator = space
+# path_separator = newline
+#
+# Use os.pathsep. Default configuration used for new projects.
+path_separator = os
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+# database URL.  This is consumed by the user-maintained env.py script only.
+# other means of configuring database URLs may be customized within the env.py
+# file.
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# lint with attempts to fix using "ruff" - use the module runner, against the "ruff" module
+# hooks = ruff
+# ruff.type = module
+# ruff.module = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Alternatively, use the exec runner to execute a binary found on your PATH
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = ruff
+# ruff.options = check --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration.  This is also consumed by the user-maintained
+# env.py script only.
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARNING
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARNING
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

backend/alembic/README

@@ -0,0 +1 @@
+Generic single-database configuration.

backend/alembic/env.py

@@ -0,0 +1,85 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+from app.core.config import settings
+from app.core.database import Base
+from app.models import models
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    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 = Base.metadata
+
+escaped_url = settings.sqlalchemy_database_url.replace('%', '%%')
+config.set_main_option("sqlalchemy.url", escaped_url)
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, target_metadata=target_metadata
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

backend/alembic/script.py.mako

@@ -0,0 +1,28 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, Sequence[str], None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    ${downgrades if downgrades else "pass"}

backend/alembic/versions/54e3661375a4_add_foreign_key_indexes.py

@@ -0,0 +1,48 @@
+"""Add foreign key indexes
+
+Revision ID: 54e3661375a4
+Revises: 
+Create Date: 2026-06-07 23:49:28.611574
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision: str = '54e3661375a4'
+down_revision: Union[str, Sequence[str], None] = None
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    op.create_index(op.f('ix_checklist_subjects_created_by'), 'checklist_subjects', ['created_by'], unique=False)
+    op.create_index(op.f('ix_checklist_topics_subject_id'), 'checklist_topics', ['subject_id'], unique=False)
+    op.create_index(op.f('ix_questions_test_id'), 'questions', ['test_id'], unique=False)
+    op.create_index(op.f('ix_test_attempts_test_id'), 'test_attempts', ['test_id'], unique=False)
+    op.create_index('ix_test_attempts_test_id_status_user_id', 'test_attempts', ['test_id', 'status', 'user_id'], unique=False)
+    op.create_index(op.f('ix_test_attempts_user_id'), 'test_attempts', ['user_id'], unique=False)
+    op.create_index(op.f('ix_test_series_created_by'), 'test_series', ['created_by'], unique=False)
+    op.create_index(op.f('ix_tests_created_by'), 'tests', ['created_by'], unique=False)
+    op.create_index(op.f('ix_tests_series_id'), 'tests', ['series_id'], unique=False)
+    op.create_index(op.f('ix_user_answers_attempt_id'), 'user_answers', ['attempt_id'], unique=False)
+    op.create_index(op.f('ix_user_answers_question_id'), 'user_answers', ['question_id'], unique=False)
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    op.drop_index(op.f('ix_user_answers_question_id'), table_name='user_answers')
+    op.drop_index(op.f('ix_user_answers_attempt_id'), table_name='user_answers')
+    op.drop_index(op.f('ix_tests_series_id'), table_name='tests')
+    op.drop_index(op.f('ix_tests_created_by'), table_name='tests')
+    op.drop_index(op.f('ix_test_series_created_by'), table_name='test_series')
+    op.drop_index(op.f('ix_test_attempts_user_id'), table_name='test_attempts')
+    op.drop_index('ix_test_attempts_test_id_status_user_id', table_name='test_attempts')
+    op.drop_index(op.f('ix_test_attempts_test_id'), table_name='test_attempts')
+    op.drop_index(op.f('ix_questions_test_id'), table_name='questions')
+    op.drop_index(op.f('ix_checklist_topics_subject_id'), table_name='checklist_topics')
+    op.drop_index(op.f('ix_checklist_subjects_created_by'), table_name='checklist_subjects')

backend/app/models/models.py

@@ -2,7 +2,7 @@ import enum
 from datetime import datetime, timezone
 
 from sqlalchemy import (JSON, Boolean, DateTime, Enum, Float,
-                        ForeignKey, Integer, String, Text, UniqueConstraint)
+                        ForeignKey, Integer, String, Text, UniqueConstraint, Index)
 from sqlalchemy.orm import relationship, Mapped, mapped_column
 
 from app.core.database import Base
@@ -82,7 +82,7 @@ class TestSeries(Base):
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
     title: Mapped[str] = mapped_column(String(500), nullable=False)
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
-    created_by: Mapped[int | None] = mapped_column(Integer, ForeignKey("users.id"))
+    created_by: Mapped[int | None] = mapped_column(Integer, ForeignKey("users.id"), index=True)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc))
 
     tests = relationship("Test", back_populates="series")
@@ -99,13 +99,13 @@ class Test(Base):
     total_marks: Mapped[float] = mapped_column(Float, default=0.0)
     pdf_filename: Mapped[str | None] = mapped_column(String(500), nullable=True)
     is_published: Mapped[bool] = mapped_column(Boolean, default=True)
-    series_id: Mapped[int | None] = mapped_column(Integer, ForeignKey("test_series.id"), nullable=True)
+    series_id: Mapped[int | None] = mapped_column(Integer, ForeignKey("test_series.id"), nullable=True, index=True)
     series_order: Mapped[int] = mapped_column(Integer, default=0)
     category: Mapped[str | None] = mapped_column(String(50), nullable=True)
     series_name: Mapped[str | None] = mapped_column(String(50), nullable=True)
     test_type: Mapped[str | None] = mapped_column(String(50), nullable=True)
     subject: Mapped[str | None] = mapped_column(String(100), nullable=True)
-    created_by: Mapped[int | None] = mapped_column(Integer, ForeignKey("users.id"))
+    created_by: Mapped[int | None] = mapped_column(Integer, ForeignKey("users.id"), index=True)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc))
 
     questions = relationship(
@@ -127,7 +127,7 @@ class Test(Base):
 class Question(Base):
     __tablename__ = "questions"
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
-    test_id: Mapped[int] = mapped_column(Integer, ForeignKey("tests.id"), nullable=False)
+    test_id: Mapped[int] = mapped_column(Integer, ForeignKey("tests.id"), nullable=False, index=True)
     question_type: Mapped[QuestionType] = mapped_column(Enum(QuestionType), default=QuestionType.mcq, nullable=False)
     question_text: Mapped[str] = mapped_column(Text, nullable=False)
     question_image_url: Mapped[str | None] = mapped_column(String(500), nullable=True)
@@ -151,8 +151,8 @@ class TestAttempt(Base):
     __test__ = False
     __tablename__ = "test_attempts"
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
-    user_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), nullable=False)
-    test_id: Mapped[int] = mapped_column(Integer, ForeignKey("tests.id"), nullable=False)
+    user_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), nullable=False, index=True)
+    test_id: Mapped[int] = mapped_column(Integer, ForeignKey("tests.id"), nullable=False, index=True)
     status: Mapped[TestStatus] = mapped_column(Enum(TestStatus), default=TestStatus.in_progress)
     started_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
     submitted_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
@@ -161,6 +161,10 @@ class TestAttempt(Base):
     tab_violations: Mapped[int] = mapped_column(Integer, default=0)
     fullscreen_violations: Mapped[int] = mapped_column(Integer, default=0)
 
+    __table_args__ = (
+        Index("ix_test_attempts_test_id_status_user_id", "test_id", "status", "user_id"),
+    )
+
     user = relationship("User", back_populates="attempts")
     test = relationship("Test", back_populates="attempts")
     answers = relationship(
@@ -187,8 +191,8 @@ class PracticeAttemptCounter(Base):
 class UserAnswer(Base):
     __tablename__ = "user_answers"
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
-    attempt_id: Mapped[int] = mapped_column(Integer, ForeignKey("test_attempts.id"), nullable=False)
-    question_id: Mapped[int] = mapped_column(Integer, ForeignKey("questions.id"), nullable=False)
+    attempt_id: Mapped[int] = mapped_column(Integer, ForeignKey("test_attempts.id"), nullable=False, index=True)
+    question_id: Mapped[int] = mapped_column(Integer, ForeignKey("questions.id"), nullable=False, index=True)
     selected_answer: Mapped[str | None] = mapped_column(String(500), nullable=True)
     is_correct: Mapped[bool | None] = mapped_column(Boolean, nullable=True)
     marks_awarded: Mapped[float] = mapped_column(Float, default=0.0)
@@ -223,7 +227,7 @@ class ChecklistSubject(Base):
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
     name: Mapped[str] = mapped_column(String(200), nullable=False)
     order_index: Mapped[int] = mapped_column(Integer, default=0)
-    created_by: Mapped[int | None] = mapped_column(Integer, ForeignKey("users.id"))
+    created_by: Mapped[int | None] = mapped_column(Integer, ForeignKey("users.id"), index=True)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=lambda: datetime.now(timezone.utc))
 
     topics = relationship(
@@ -234,7 +238,7 @@ class ChecklistSubject(Base):
 class ChecklistTopic(Base):
     __tablename__ = "checklist_topics"
     id: Mapped[int] = mapped_column(Integer, primary_key=True, index=True)
-    subject_id: Mapped[int] = mapped_column(Integer, ForeignKey("checklist_subjects.id"), nullable=False)
+    subject_id: Mapped[int] = mapped_column(Integer, ForeignKey("checklist_subjects.id"), nullable=False, index=True)
     name: Mapped[str] = mapped_column(String(200), nullable=False)
     order_index: Mapped[int] = mapped_column(Integer, default=0)