Add index on block number to make delete quick

alembic/versions/c5da44eb072c_add_index_for_classified_traces_block_.py

@@ -0,0 +1,24 @@
+"""Add index for classified_traces.block_number
+
+Revision ID: c5da44eb072c
+Revises: 0660432b9840
+Create Date: 2021-07-30 17:37:27.335475
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'c5da44eb072c'
+down_revision = '0660432b9840'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_index('i_block_number', 'classified_traces', ['block_number'])
+
+
+def downgrade():
+    op.drop_index('i_block_number', 'classified_traces')