add app mode for message (#26876)

api/migrations/versions/2025_10_14_1618-d98acf217d43_add_app_mode_for_messsage.py

@@ -0,0 +1,84 @@
+"""add app_mode for messsage
+
+Revision ID: d98acf217d43
+Revises: 68519ad5cd18
+Create Date: 2025-10-14 16:18:08.568011
+
+"""
+from alembic import op
+import models as models
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = 'd98acf217d43'
+down_revision = '68519ad5cd18'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    with op.batch_alter_table('messages', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('app_mode', sa.String(length=255), nullable=True))
+        batch_op.create_index('message_app_mode_idx', ['app_mode'], unique=False)
+
+    conn = op.get_bind()
+    
+    # Strategy: Update in batches to minimize lock time
+    # For large tables (millions of rows), this prevents long-running transactions
+    batch_size = 10000
+    
+    print("Starting backfill of app_mode from conversations...")
+    
+    # Use a more efficient UPDATE with JOIN
+    # This query updates messages.app_mode from conversations.mode
+    # Using string formatting for LIMIT since it's a constant
+    update_query = f"""
+        UPDATE messages m
+        SET app_mode = c.mode
+        FROM conversations c
+        WHERE m.conversation_id = c.id
+          AND m.app_mode IS NULL
+          AND m.id IN (
+              SELECT id FROM messages 
+              WHERE app_mode IS NULL 
+              LIMIT {batch_size}
+          )
+    """
+    
+    # Execute batched updates
+    total_updated = 0
+    iteration = 0
+    while True:
+        iteration += 1
+        result = conn.execute(sa.text(update_query))
+        
+        # Check if result is None or has no rowcount
+        if result is None:
+            print("Warning: Query returned None, stopping backfill")
+            break
+            
+        rows_updated = result.rowcount if hasattr(result, 'rowcount') else 0
+        total_updated += rows_updated
+        
+        if rows_updated == 0:
+            break
+            
+        print(f"Iteration {iteration}: Updated {rows_updated} messages (total: {total_updated})")
+        
+        # For very large tables, add a small delay to reduce load
+        # Uncomment if needed: import time; time.sleep(0.1)
+    
+    print(f"Backfill completed. Total messages updated: {total_updated}")
+
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+
+    with op.batch_alter_table('messages', schema=None) as batch_op:
+        batch_op.drop_index('message_app_mode_idx')
+        batch_op.drop_column('app_mode')
+
+    # ### end Alembic commands ###