Q:

rake jobs:work gives "PGError: ERROR: SELECT FOR UPDATE/SHARE is not allowed in subqueries"

I'm merging in some changes to my Rails app, which include the addition of the delayed_job gem (which looks AWESOME). To test it out, I:

ran rails g delayed_job 
ran rake db:migrate, which created the delayed_jobs table
restarted rails server (just in case)
restarted the postgresql service (just in case)
ran scripts/delayed_job start 
performed some tasks to accrue delayed jobs 

But nothing happened :/ My jobs are in the delayed jobs table, but locked_at is null (As is last_error).
So I tried rake jobs:work, which gave a strange Postgres error:
PGError: ERROR:  SELECT FOR UPDATE/SHARE is not allowed in subqueries
and a trace:
$ 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)

I can't figure out what's wrong -- and more surprisingly, I can find anyone else asking this question....! 
Thanks for any help!

A:

I had the exact same problem.  I solved this by locking my Gemfile for delayed_job_active_record to version 0.3.3:
gem 'delayed_job_active_record', '0.3.3'
The non-working gem was version 0.4.1, which was released on February 12, 2012.

A:

Updating postgres fixed the problem for me too--and that seems preferable to locking back to an old version.  Not that this is my answer, but as rmosolgo answered his own question it does seem like this question could properly go into 'accepted answer' state.

