PostgreSQL < 9.3 does not respect a new search_path for prepared statements

[meganemura]

@mikecmpbll

I finally straighten out the failing spec with PostgreSQL + Rails 5.0 + Apartment that I described in #448.

The issue is caused by older PostgreSQL version (< 9.3). That version of PostgreSQL behaves a supprising behavior (as official document described in E.18.2.2. Other) for the cached statements.

Force cached plans to be replanned if the search_path changes (Tom Lane)
Previously, cached plans already generated in the current session were not redone if the query was re-executed with a new search_path setting, resulting in surprising behavior.

And the PREPARE statement documentation is here: https://www.postgresql.org/docs/9.3/static/sql-prepare.html

Remarkable point:

Also, if the value of search_path changes from one use to the next, the statement will be re-parsed using the new search_path. (This latter behavior is new as of PostgreSQL 9.3.)

So, clearing the cache of prepared statements for the older version of PostgreSQL is to solve the problem about the tests.

You can confirm what the statements are cached in the specs by adding the lines below.

p Apartment.connection.instance_variable_get(:@statements)

The query for the ar_internal_metadata are cached and executed for a removed schema under PostgreSQL 9.1 (default version for the Travis-CI), so the test is failed with PG::UndefinedTable: ERROR: relation "ar_internal_metadata" does not exist at character 39.

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And I fixed some rarely (occasionally?) failing spec.

[mikecmpbll]

love love love this ❤️. thanks so much for doing the digging.

any ideas on the jruby fails?

[meganemura]

any ideas on the jruby fails?

No 😩 I'm not familiar with JRuby.
I started setup a docker file for jruby envs to reproduce and dig it the failure.

[meganemura]

I figured out 🎉
Failures in 4.2 and 5.0 are the JRuby issue. Here is the related issue at rails/rails.
rails/rails#28342
Newer rails must be run by JRuby > 9.1.9.0.

And the another problem is activerecord-jdbc-adapter, not apartment.
jruby/activerecord-jdbc-adapter#700
I have tested against Rails 5.0 with activerecord-jdbc-adapter (rails-5 branch), but it's failed.
activerecord-jdbc-adapter for rails 5.0 is unstable and not officially supprted.
So, I exclude 5.0 + JRuby from Travis-CI build. What do you think?

[meganemura]

✅ test passed

[mikecmpbll]

yayyyy 💃

[meganemura]

Thanks 🎉