Opt database bootstrapping

src/ffx/database.py

@@ -1,6 +1,6 @@
 import os, click
 
-from sqlalchemy import create_engine
+from sqlalchemy import create_engine, inspect
 from sqlalchemy.orm import sessionmaker
 
 # Import the full model package so SQLAlchemy registers every mapped class
@@ -14,6 +14,7 @@ from ffx.constants import DATABASE_VERSION
 
 
 DATABASE_VERSION_KEY = 'database_version'
+EXPECTED_TABLE_NAMES = set(Base.metadata.tables.keys())
 
 class DatabaseVersionException(Exception):
     def __init__(self, errorMessage):
@@ -37,7 +38,7 @@ def databaseContext(databasePath: str = ''):
     databaseContext['engine'] = create_engine(databaseContext['url'])
     databaseContext['session'] = sessionmaker(bind=databaseContext['engine'])
 
-    Base.metadata.create_all(databaseContext['engine'])
+    bootstrapDatabaseIfNeeded(databaseContext)
 
     # isSyncronuous = False
     # while not isSyncronuous:
@@ -54,6 +55,19 @@ def databaseContext(databasePath: str = ''):
 
     return databaseContext
 
+
+def databaseNeedsBootstrap(databaseContext) -> bool:
+    inspector = inspect(databaseContext['engine'])
+    existingTableNames = set(inspector.get_table_names())
+    return not EXPECTED_TABLE_NAMES.issubset(existingTableNames)
+
+
+def bootstrapDatabaseIfNeeded(databaseContext):
+    if not databaseNeedsBootstrap(databaseContext):
+        return
+
+    Base.metadata.create_all(databaseContext['engine'])
+
 def ensureDatabaseVersion(databaseContext):
 
     currentDatabaseVersion = getDatabaseVersion(databaseContext)