fix: remove index_exists check to avoid transaction conflict in migration

- Remove index_exists function that used op.get_bind() within transaction
- Use IF NOT EXISTS / IF EXISTS SQL syntax instead
- Fixes CREATE INDEX CONCURRENTLY error in Docker migration

alembic/versions/20251220_1500_add_usage_composite_indexes.py

@@ -6,7 +6,7 @@ Create Date: 2025-12-20 15:00:00.000000+00:00
 
 """
 from alembic import op
-from sqlalchemy import inspect, text
+from sqlalchemy import text
 
 # revision identifiers, used by Alembic.
 revision = 'b2c3d4e5f6g7'
@@ -15,14 +15,6 @@ branch_labels = None
 depends_on = None
 
 
-def index_exists(table_name: str, index_name: str) -> bool:
-    """检查索引是否存在"""
-    bind = op.get_bind()
-    inspector = inspect(bind)
-    indexes = [idx['name'] for idx in inspector.get_indexes(table_name)]
-    return index_name in indexes
-
-
 def upgrade() -> None:
     """为 usage 表添加复合索引以优化常见查询
 
@@ -34,35 +26,38 @@ def upgrade() -> None:
 
     # 使用新连接并设置 AUTOCOMMIT 模式以支持 CREATE INDEX CONCURRENTLY
     with engine.connect().execution_options(isolation_level="AUTOCOMMIT") as autocommit_conn:
+        # 使用 IF NOT EXISTS 避免重复创建，无需单独检查索引是否存在
+
         # 1. user_id + created_at 复合索引 (用户用量查询)
-        if not index_exists('usage', 'idx_usage_user_created'):
-            autocommit_conn.execute(text(
-                "CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_user_created "
-                "ON usage (user_id, created_at)"
-            ))
+        autocommit_conn.execute(text(
+            "CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_user_created "
+            "ON usage (user_id, created_at)"
+        ))
 
         # 2. api_key_id + created_at 复合索引 (API Key 用量查询)
-        if not index_exists('usage', 'idx_usage_apikey_created'):
-            autocommit_conn.execute(text(
-                "CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_apikey_created "
-                "ON usage (api_key_id, created_at)"
-            ))
+        autocommit_conn.execute(text(
+            "CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_apikey_created "
+            "ON usage (api_key_id, created_at)"
+        ))
 
         # 3. provider + model + created_at 复合索引 (模型统计查询)
-        if not index_exists('usage', 'idx_usage_provider_model_created'):
-            autocommit_conn.execute(text(
-                "CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_provider_model_created "
-                "ON usage (provider, model, created_at)"
-            ))
+        autocommit_conn.execute(text(
+            "CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_usage_provider_model_created "
+            "ON usage (provider, model, created_at)"
+        ))
 
 
 def downgrade() -> None:
     """删除复合索引"""
-    if index_exists('usage', 'idx_usage_provider_model_created'):
-        op.drop_index('idx_usage_provider_model_created', table_name='usage')
+    conn = op.get_bind()
 
-    if index_exists('usage', 'idx_usage_apikey_created'):
-        op.drop_index('idx_usage_apikey_created', table_name='usage')
-
-    if index_exists('usage', 'idx_usage_user_created'):
-        op.drop_index('idx_usage_user_created', table_name='usage')
+    # 使用 IF EXISTS 避免索引不存在时报错
+    conn.execute(text(
+        "DROP INDEX IF EXISTS idx_usage_provider_model_created"
+    ))
+    conn.execute(text(
+        "DROP INDEX IF EXISTS idx_usage_apikey_created"
+    ))
+    conn.execute(text(
+        "DROP INDEX IF EXISTS idx_usage_user_created"
+    ))