query-patterns 0.1.9

Lightweight query access-pattern declaration for ORMs

query-patterns

Declare query-access patterns in code and verify matching DB indexes. Supports SQLAlchemy and Django, both schema-based and database introspection modes.

Motivation

As projects grow, the number and variety of database queries increase. Over time, it becomes difficult to maintain a consistent set of query-access patterns across the codebase, and even harder to verify whether each pattern is backed by an appropriate database index. Relying on manual checks or memory often leads to:

• Missing or outdated indexes that cause silent performance regressions
• Inconsistent query patterns across teams or modules
• Schema changes that unintentionally break previously optimized queries
• Performance issues that surface only in production traffic

query-patterns addresses these problems by allowing you to declare expected query patterns in code and validate them against either your ORM schema or a running database instance — all via a simple CLI command.

What it does

• Collects all @query_pattern declarations from your Python modules
• Extracts index definitions from:
  • SQLAlchemy
    • ORM schema (MetaData)
    • Actual DB (Inspector)
  • Django
    • ORM schema (Model._meta.indexes)
    • Actual DB (connection.introspection)
• Compares (table, columns) tuples
• Can be integrated into CI to enforce index coverage

Install

pip install query-patterns

Declare a pattern

from query_patterns import query_pattern


# Declare query pattern using table/column names
class RepoA:
    @query_pattern(table="users", columns=["email"])
    def find(self, email): ...


# Declare query pattern using ORM models(works with both SQLAlchemy and Django models)
from models import User

class RepoB:
    @query_pattern(table=User, columns=[User.email])
    def find(self, email): ...

a. SQLAlchemy Command

# Reads indexes from MetaData
query-patterns sqlalchemy \
  --metadata myapp.db.metadata \
  --module myapp.repo
  
# Auto-discover modules
query-patterns sqlalchemy \
  --metadata myapp.db.metadata
  
# Reads actual indexes from the database
query-patterns sqlalchemy \
  --source db \
  --engine-url postgresql://user:pass@localhost/mydb \
  --module myapp.repo

b. Django Command

# Reads Model._meta.indexes from installed apps
query-patterns django \
  --settings config.settings \
  --module myapp.repo
  
# Auto-discover modules 
query-patterns django \
  --settings config.settings
  
# Reads actual DB indexes using Django introspection
query-patterns django \
  --source db \
  --settings config.settings \
  --module myapp.repo