Cloning a database from one Discourse to another causes rebuild to fail on migration

Hello.

I have two instances of discourse, let’s call them Beta and Dev. Beta is more “correct” than Dev, in that it has the settings/initial data that we want in the final. Dev is where we play around with plugins, themes.

Now I want to clone the Beta DB for our Dev instance to use, so that we can see how our changes to the plugin/themes would look in Beta (without touching Beta). But after cloning the database, and pointing my app.yml to use the new database, migration is failing. What I did:

  1. Generated backup.sql of Beta db (except user_histories, stylesheet_cache and scheduler_stats, to make it faster)
  2. Created new Dev db
  3. Restored backup.sql onto new Dev db
  4. Point app.yml to the new Dev db and run rebuild.

Resulting Error log below:

Caused by:
PG::SyntaxError: ERROR:  zero-length delimited identifier at or near """"
LINE 1: ...ECT 1 AS one FROM "categories" WHERE "categories"."" = 1 LIM...
                                                             ^
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/rack-mini-profiler-2.2.0/lib/patches/db/pg.rb:69:in `exec_params'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/rack-mini-profiler-2.2.0/lib/patches/db/pg.rb:69:in `exec_params'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/postgresql_adapter.rb:675:in `block (2 levels) in exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/postgresql_adapter.rb:674:in `block in exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract_adapter.rb:722:in `block (2 levels) in log'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract_adapter.rb:721:in `block in log'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract_adapter.rb:712:in `log'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/postgresql_adapter.rb:673:in `exec_no_cache'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/postgresql_adapter.rb:654:in `execute_and_clear'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/postgresql/database_statements.rb:98:in `exec_query'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/database_statements.rb:489:in `select'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/database_statements.rb:70:in `select_all'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/query_cache.rb:107:in `select_all'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/database_statements.rb:77:in `select_one'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/relation/finder_methods.rb:317:in `block in exists?'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/relation.rb:839:in `skip_query_cache_if_necessary'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/relation/finder_methods.rb:317:in `exists?'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/querying.rb:21:in `exists?'
/var/www/discourse/lib/seed_data/categories.rb:132:in `should_create_category?'
/var/www/discourse/lib/seed_data/categories.rb:102:in `create_category'
/var/www/discourse/lib/seed_data/categories.rb:15:in `block (2 levels) in create'
/var/www/discourse/lib/seed_data/categories.rb:15:in `each'
/var/www/discourse/lib/seed_data/categories.rb:15:in `block in create'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/i18n-1.8.5/lib/i18n.rb:313:in `with_locale'
/var/www/discourse/lib/seed_data/categories.rb:14:in `create'
(eval):6:in `block (2 levels) in run_file'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:46:in `eval'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:46:in `block (2 levels) in run_file'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:58:in `block in open'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:57:in `open'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:57:in `open'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:36:in `block in run_file'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in `block in transaction'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/transaction.rb:280:in `block in within_new_transaction'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activesupport-6.0.3.3/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/transaction.rb:278:in `within_new_transaction'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/connection_adapters/abstract/database_statements.rb:280:in `transaction'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/activerecord-6.0.3.3/lib/active_record/transactions.rb:212:in `transaction'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:35:in `run_file'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:26:in `block in run'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:25:in `each'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu/runner.rb:25:in `run'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/seed-fu-2.3.9/lib/seed-fu.rb:29:in `seed'
/var/www/discourse/lib/tasks/db.rake:222:in `block in <main>'
/var/www/discourse/vendor/bundle/ruby/2.7.0/gems/rake-13.0.1/exe/rake:27:in `<top (required)>'
/usr/local/bin/bundle:23:in `load'
/usr/local/bin/bundle:23:in `<main>'
Tasks: TOP => db:migrate

I realize a full clone might be problematic, but could you give an idea of what the problem might be? Also, am I doing this The Noob Way? Are there tools and processes you would have used instead to clone a discourse instance?

Thanks.

Are both instances the same version of Discourse?

It’ll be much easier if you just use the built in backup and restore. Just make sure that the site that you’re restoring to is at least as new as the one where you make the backup.

2 Likes

There it is. The Proper Way. Thanks for educating this noob.

1 Like

Happy to help! It’s hard to learn a new way of doing things. I’ll often say “oh, they thought of that!”

If you be both sites share the same S3 bucket for v backups then you don’t have to transfer the backup between the sites! You can also do the backup and restore from the command line (there’s a topic about that).

1 Like