我正在 Rails 应用程序中的包含很多行的表上运行以下迁移：
rake db:migrate
*** [] rake aborted!
*** [] An error has occurred, this and all later migrations canceled:
*** []
*** [] PG::Error: ERROR: deadlock detected
*** [] DETAIL: Process 33319 waits for AccessExclusiveLock on relation 18486 of database 16948; blocked by process 29772.
*** [] Process 29772 waits for ShareLock on transaction 8652; blocked by process 33319.
*** [] HINT: See server log for query details.
*** [] : ALTER TABLE "topics" DROP "most_recent_post_id"
*** [] …