./pt-online-schema-change --alter "CHANGE \`email\` \`email\` VARCHAR(191) COLLATE utf8_unicode_ci DEFAULT NULL, CHANGE \`uid\` \`uid\` VARCHAR(191) CHARACTER SET utf8 DEFAULT NULL" D=VerifyValid,t=lockboxes --execute --alter-foreign-keys-method=auto
Found 1 slaves:
ip-10-69-60-130 -> ey-db-slave:socket
Will check slave lag on:
ip-10-69-60-130 -> ey-db-slave:socket
Operation, tries, wait:
  analyze_table, 10, 1
  copy_rows, 10, 0.25
  create_triggers, 10, 1
  drop_triggers, 10, 1
  swap_tables, 10, 1
  update_foreign_keys, 10, 1
Child tables:
  `VerifyValid`.`affiliates` (approx. 7 rows)
  `VerifyValid`.`lockbox_batches` (approx. 20315 rows)
Will automatically choose the method to update foreign keys.
Altering `VerifyValid`.`lockboxes`...
Creating new table...
Created new table VerifyValid._lockboxes_new OK.
Waiting forever for new table `VerifyValid`.`_lockboxes_new` to replicate to ip-10-69-60-130...
Altering new table...
Altered `VerifyValid`.`_lockboxes_new` OK.
2017-11-16T18:37:49 Creating triggers...
2017-11-16T18:37:49 Created triggers OK.
2017-11-16T18:37:49 Copying approximately 198196 rows...
2017-11-16T18:37:57 Copied rows OK.
2017-11-16T18:37:57 Max rows for the rebuild_constraints method: 58880
Determining the method to update foreign keys...
2017-11-16T18:37:57   `VerifyValid`.`affiliates`: 7 rows; can use rebuild_constraints
2017-11-16T18:37:57   `VerifyValid`.`lockbox_batches`: 20315 rows; can use rebuild_constraints
2017-11-16T18:37:57 Analyzing new table...
2017-11-16T18:37:57 Swapping tables...
2017-11-16T18:37:57 Swapped original and new tables OK.
2017-11-16T18:37:57 Rebuilding foreign key constraints...
2017-11-16T18:37:58 Rebuilt foreign key constraints OK.
2017-11-16T18:37:58 Dropping old table...
2017-11-16T18:37:58 Dropped old table `VerifyValid`.`_lockboxes_old` OK.
2017-11-16T18:37:58 Dropping triggers...
2017-11-16T18:37:58 Dropped triggers OK.
Successfully altered `VerifyValid`.`lockboxes`.