我正在合并我的 Rails 应用程序的一些更改，其中包括添加延迟作业 gem（看起来很棒）。为了测试它，我：
- 跑了
rails g delayed_job - ran
rake db:migrate，它创建了delayed_jobs 表 - 重新启动
rails server（以防万一） - 重新启动 postgresql 服务（以防万一）
- 跑了
scripts/delayed_job start - 执行了一些任务以累积延迟的工作
但是什么也没发生：/我的工作在延迟工作表中，但locked_at为空（原样last_error）。
所以我尝试rake jobs:work了，它给出了一个奇怪的 Postgres 错误：
PGError: ERROR: SELECT FOR UPDATE/SHARE is not allowed in subqueries
和一个跟踪：
$ rake jobs:work
[Worker(host:robert-vaio pid:21217)] Starting job worker
rake aborted!
PGError: ERROR: SELECT FOR UPDATE/SHARE is not allowed in subqueries
: UPDATE "delayed_jobs" SET locked_at = '2013-02-13 19:53:46.803085', locked_by = 'host:robert-vaio pid:21217' WHERE id IN (SELECT id FROM "delayed_jobs" WHERE ((run_at <= '2013-02-13 19:53:46.792619' AND (locked_at IS NULL OR locked_at < '2013-02-13 15:53:46.792639') OR locked_by = 'host:robert-vaio pid:21217') AND failed_at IS NULL) ORDER BY priority ASC, run_at ASC LIMIT 1 FOR UPDATE) RETURNING *
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/postgresql_adapter.rb:1153:in `async_exec'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/postgresql_adapter.rb:1153:in `exec_no_cache'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/postgresql_adapter.rb:662:in `block in exec_query'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `block in log'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activesupport-3.2.12/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/postgresql_adapter.rb:661:in `exec_query'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/postgresql_adapter.rb:1248:in `select'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/database_statements.rb:18:in `select_all'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/connection_adapters/abstract/query_cache.rb:63:in `select_all'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/querying.rb:38:in `block in find_by_sql'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/explain.rb:33:in `logging_query_plan'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/activerecord-3.2.12/lib/active_record/querying.rb:37:in `find_by_sql'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job_active_record-0.4.1/lib/delayed/backend/active_record.rb:63:in `reserve'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:258:in `reserve_and_run_one_job'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:187:in `block in work_off'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:186:in `times'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:186:in `work_off'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:151:in `block (4 levels) in start'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:150:in `block (3 levels) in start'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:60:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:60:in `block in initialize'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:65:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:65:in `execute'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:38:in `run_callbacks'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:149:in `block (2 levels) in start'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:148:in `loop'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:148:in `block in start'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/plugins/clear_locks.rb:7:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/plugins/clear_locks.rb:7:in `block (2 levels) in <class:ClearLocks>'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:78:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:78:in `block (2 levels) in add'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:60:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:60:in `block in initialize'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:78:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:78:in `block in add'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:65:in `call'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:65:in `execute'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/lifecycle.rb:38:in `run_callbacks'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/worker.rb:147:in `start'
/home/robert/.rvm/gems/ruby-1.9.3-p327/gems/delayed_job-3.0.5/lib/delayed/tasks.rb:9:in `block (2 levels) in <top (required)>'
Tasks: TOP => jobs:work
(See full trace by running task with --trace)
我不知道出了什么问题——更令人惊讶的是，我能找到其他人问这个问题......！
谢谢你的帮助！