Error merging users with duplicate poll votes

Contribute Bug

AI-generated summary

A bug has been identified when merging users with duplicate poll votes, causing the merge to fail. rollerbob encountered this issue and found that deleting one of the conflicting votes allowed the merge to succeed. Others, including jhogendorn and JammyDodger, have also replicated the issue.

When the merge fails, the source user may still appear to exist and be able to log in, but their posts are assigned to the target user. JammyDodger observed this behavior in their test site.

The team is working on a fix, favoring the target user’s vote in cases of duplicates. A pull request has been submitted to address this issue. sam estimates that the fix will be available in a few weeks. nat has also provided additional context and insights into the bug, highlighting the complexity of the issue.

1

Relevant part of the error

rake aborted!
ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR:  duplicate key value violates unique constraint "index_poll_votes_on_poll_id_and_poll_option_id_and_user_id"
DETAIL:  Key (poll_id, poll_option_id, user_id)=(129, 559, 582) already exists.

I checked the poll_votes table and the target and source users did vote with the same option.
Merge worked fine after I deleted one of the conflicting votes.

Full error

Summary 
** Invoke users:merge (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute users:merge
rake aborted!
ActiveRecord::RecordNotUnique: PG::UniqueViolation: ERROR:  duplicate key value violates unique constraint "index_poll_votes_on_poll_id_and_poll_option_id_and_user_id"
DETAIL:  Key (poll_id, poll_option_id, user_id)=(129, 559, 582) already exists.
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rack-mini-profiler-2.0.2/lib/patches/db/pg.rb:69:in `exec_params'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rack-mini-profiler-2.0.2/lib/patches/db/pg.rb:69:in `exec_params'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `block (2 levels) in exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:674:in `block in exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:722:in `block (2 levels) in log'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:721:in `block in log'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:712:in `log'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:673:in `exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:654:in `execute_and_clear'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:111:in `exec_delete'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/database_statements.rb:174:in `update'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/query_cache.rb:22:in `update'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/relation.rb:469:in `update_all'
/var/www/discourse/plugins/poll/plugin.rb:560:in `block (2 levels) in activate!'
/var/www/discourse/lib/plugin/instance.rb:348:in `block in on'
/var/www/discourse/lib/discourse_event.rb:14:in `block in trigger'
/usr/local/lib/ruby/2.6.0/set.rb:338:in `each_key'
/usr/local/lib/ruby/2.6.0/set.rb:338:in `each'
/var/www/discourse/lib/discourse_event.rb:13:in `trigger'
/var/www/discourse/app/services/user_merger.rb:21:in `merge!'
/var/www/discourse/lib/tasks/users.rake:50:in `block in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:279:in `block in execute'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:279:in `each'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:279:in `execute'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:219:in `block in invoke_with_call_chain'
/usr/local/lib/ruby/2.6.0/monitor.rb:235:in `mon_synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:199:in `invoke_with_call_chain'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:188:in `invoke'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:160:in `invoke_task'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:116:in `block (2 levels) in top_level'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:116:in `each'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:116:in `block in top_level'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:125:in `run_with_threads'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:110:in `top_level'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:83:in `block in run'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:186:in `standard_exception_handling'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:80:in `run'
bin/rake:13:in `<top (required)>'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb:63:in `load'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb:63:in `kernel_load'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb:28:in `run'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli.rb:476:in `exec'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor.rb:399:in `dispatch'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli.rb:30:in `dispatch'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor/base.rb:476:in `start'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli.rb:24:in `start'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/exe/bundle:46:in `block in <top (required)>'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/friendly_errors.rb:123:in `with_friendly_errors'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/exe/bundle:34:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'

Caused by:
PG::UniqueViolation: ERROR:  duplicate key value violates unique constraint "index_poll_votes_on_poll_id_and_poll_option_id_and_user_id"
DETAIL:  Key (poll_id, poll_option_id, user_id)=(129, 559, 582) already exists.
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rack-mini-profiler-2.0.2/lib/patches/db/pg.rb:69:in `exec_params'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rack-mini-profiler-2.0.2/lib/patches/db/pg.rb:69:in `exec_params'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `block (2 levels) in exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:674:in `block in exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:722:in `block (2 levels) in log'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:721:in `block in log'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:712:in `log'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:673:in `exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql_adapter.rb:654:in `execute_and_clear'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:111:in `exec_delete'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/database_statements.rb:174:in `update'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/query_cache.rb:22:in `update'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/relation.rb:469:in `update_all'
/var/www/discourse/plugins/poll/plugin.rb:560:in `block (2 levels) in activate!'
/var/www/discourse/lib/plugin/instance.rb:348:in `block in on'
/var/www/discourse/lib/discourse_event.rb:14:in `block in trigger'
/usr/local/lib/ruby/2.6.0/set.rb:338:in `each_key'
/usr/local/lib/ruby/2.6.0/set.rb:338:in `each'
/var/www/discourse/lib/discourse_event.rb:13:in `trigger'
/var/www/discourse/app/services/user_merger.rb:21:in `merge!'
/var/www/discourse/lib/tasks/users.rake:50:in `block in <top (required)>'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:279:in `block in execute'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:279:in `each'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:279:in `execute'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:219:in `block in invoke_with_call_chain'
/usr/local/lib/ruby/2.6.0/monitor.rb:235:in `mon_synchronize'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:199:in `invoke_with_call_chain'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/task.rb:188:in `invoke'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:160:in `invoke_task'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:116:in `block (2 levels) in top_level'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:116:in `each'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:116:in `block in top_level'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:125:in `run_with_threads'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:110:in `top_level'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:83:in `block in run'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:186:in `standard_exception_handling'
/var/www/discourse/vendor/bundle/ruby/2.6.0/gems/rake-13.0.1/lib/rake/application.rb:80:in `run'
bin/rake:13:in `<top (required)>'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb:63:in `load'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb:63:in `kernel_load'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb:28:in `run'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli.rb:476:in `exec'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor/command.rb:27:in `run'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor/invocation.rb:127:in `invoke_command'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor.rb:399:in `dispatch'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli.rb:30:in `dispatch'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/vendor/thor/lib/thor/base.rb:476:in `start'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/cli.rb:24:in `start'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/exe/bundle:46:in `block in <top (required)>'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/lib/bundler/friendly_errors.rb:123:in `with_friendly_errors'
/usr/local/lib/ruby/gems/2.6.0/gems/bundler-2.1.4/exe/bundle:34:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'
Tasks: TOP => users:merge
4 Likes
3

Have just run into this issue myself. its still very much an issue on latest.

1 Like
4

I can replicate this on my test site. (107239a442)

  • Create poll
  • Test_User_One and Test_User_Two vote for the same poll option
  • Merge Test_User_Two into Test_User_One
  • Process gets stuck on ‘Merge Progress’ modal

merge progress
merge progress1080×1243 76 KB

Though saying that, after navigating away from the hanging modal, Test_User_Two appears to have vanished. I should have given them some posts to see if the merge was actually completed. Back in a minute. :slightly_smiling_face:

Very interestingly, Test_User_Two does not show up in my admin ‘active users’ list, but can still log in and post.

Update: It seems to have updated itself a little now, and Test_Two’s posts have been assigned to Test_One. I’m still logged in as Test_Two though, with a Test_Two Summary page, etc. I’ve even logged out, and logged back in again with Test_Two’s credentials.

Sorry, I was finding the quirks very interesting. They perhaps might not be useful. :slightly_smiling_face:

4 Likes
5

Quick update, this is on our list to sort out, we hope to have it sorted in a few weeks.

4 Likes
10

This one’s a fun bug.

Due to poll votes not merging properly, when we merge Lancelot (id 383) → Galahad (id 120), Lancelot actually would still exist, but not have a primary email - /admin/users/383/lancelot would error with http 500 due to an anonymization check.

Anyway we’ve got a fix on the way. We’re favouring keeping Galahad’s (the target user) vote in this case of duplicates.

https://github.com/discourse/discourse/pull/22105

https://github.com/discourse/discourse/pull/22107

4 Likes
11

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