increase db pool size

backend/oasst_backend/config.py

@@ -166,6 +166,9 @@ class Settings(BaseSettings):
     DATABASE_URI: Optional[PostgresDsn] = None
     DATABASE_MAX_TX_RETRY_COUNT: int = 3
 
+    DATABASE_POOL_SIZE = 128
+    DATABASE_MAX_OVERFLOW = 128
+
     RATE_LIMIT: bool = True
     MESSAGE_SIZE_LIMIT: int = 2000
     REDIS_HOST: str = "localhost"

backend/oasst_backend/database.py

@@ -5,4 +5,10 @@ from sqlmodel import create_engine
 if settings.DATABASE_URI is None:
     raise OasstError("DATABASE_URI is not set", error_code=OasstErrorCode.DATABASE_URI_NOT_SET)
 
-engine = create_engine(settings.DATABASE_URI, echo=settings.DEBUG_DATABASE_ECHO, isolation_level="REPEATABLE READ")
+engine = create_engine(
+    settings.DATABASE_URI,
+    echo=settings.DEBUG_DATABASE_ECHO,
+    isolation_level="REPEATABLE READ",
+    pool_size=settings.DATABASE_POOL_SIZE,
+    max_overflow=settings.DATABASE_MAX_OVERFLOW,
+)