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app/database.py

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+import logging
+import os
+
+from sqlalchemy import create_engine, event
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+from sqlalchemy.pool import QueuePool
+
+logger = logging.getLogger(__name__)
+
+# Remove hardcoded credentials - require environment variable
+DATABASE_URL = os.getenv("DATABASE_URL")
+
+if not DATABASE_URL:
+    raise ValueError(
+        "DATABASE_URL environment variable is required. Example: postgresql://user:password@localhost:5432/pricewatch"
+    )
+
+# Connection pool configuration
+#  pool_size: number of connections to maintain
+#  max_overflow: max number of connections above pool_size
+#  pool_pre_ping: verify connections before using (prevents stale connections)
+#  pool_recycle: recycle connections after N seconds (prevents timeout issues)
+engine = create_engine(
+    DATABASE_URL,
+    poolclass=QueuePool,
+    pool_size=5,
+    max_overflow=10,
+    pool_pre_ping=True,
+    pool_recycle=3600,  # 1 hour
+    echo=os.getenv("SQL_ECHO", "false").lower() == "true",
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()
+
+
+# Log database connection events for debugging
+@event.listens_for(engine, "connect")
+def receive_connect(dbapi_conn, connection_record):
+    logger.debug("Database connection established")
+
+
+@event.listens_for(engine, "close")
+def receive_close(dbapi_conn, connection_record):
+    logger.debug("Database connection closed")
+
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    except Exception:
+        db.rollback()
+        raise
+    finally:
+        db.close()