skip_schema_queries setting seems to be ignored in development

[toupeira]

I can't seem to change the skip_schema_queries setting to true in the development environment, I tried setting Rack::MiniProfiler.config.skip_schema_queries directly in the initializer and also using a Rails.configuration.after_initialize block, but I still get the schema queries in the profiler output. Is there anything I'm missing? I did restart my server several times and made sure there were no old Ruby processes hanging around.

[vitaly]

from what I can see in the source its only handled on "weird dbs" and the handling is funny:

      return rval if Rack::MiniProfiler.config.skip_schema_queries and name =~ /SCHEMA/

There seems to be no support for postgres for example.

[toupeira]

I think that check is fine since ActiveRecord is setting that SCHEMA part (in the PostgreSQL adapter too). I'm more curious about these lines in railtie.rb:

if Rails.env.development?
  c.skip_paths << "/assets/"
  c.skip_schema_queries = true
end

And further down:

c.skip_schema_queries =  Rails.env != 'production'

So unless I'm missing something skip_schema_queries seems to be hard-coded depending on the environment.

[vitaly]

no its not ok, it simply doesn't work. once postgres is detected this part of the code doesn't execute. those lines are only for 'unknown databases'

[toupeira]

Ah sorry, didn't bother to look at the rest of the file ;-)

So there are two issues:

• skip_schema_queries is ignored for all default DB providers and only used in the fallback code (see sql_patches.rb)
• skip_schema_queries is hard-coded to true in production and false everywhere else (see railtie.rb)

[vitaly]

still no ;) its hardcoded to false in production and true everywhere else, which kind of makes sense.

[toupeira]

Damn, I should triple-check my comments before posting ;-)

Hard-coding for development doesn't make sense to me at all though, why should I care about the execution length of schema queries which will be cached on production anyway? And they make it hard to notice the actual queries among all the noise.

[vitaly]

I think the motivation is that ​ignoring schema changes is a heuristic, so in production you don't want any of that, especially as they don't really happen anyway. But you should be willing to tolerate it in development, where schema queries are a pain.