This adapter ensures that MiniSql locks the ActiveRecord mutex before using the raw PG connection. This ensures that multiple threads will not attempt to use the same connection simultaneously.
This commit also removes the schema_cache_concurrency freedom-patch, which is no longer required now that cross-thread connection use is controlled by the mutex.
For the original root cause of this issue, see https://github.com/rails/rails/pull/38577
* DEV: upgrade mini_sql
Even though we are not planning on using this quite yet, mini_sql now supports
prepared statements.
Would like this upgrade merged so we can do some benchmarking.
Note, this will not work with pg_bouncer, but sites that are not using it
may benefit from the feature.
* implement multisite friendly prepared statements
Previously it matched the behavior of standard ActiveRecord after_commit callbacks. They do not work well within `joinable: false` nested transactions. Now `DB.after_commit` callbacks will only be run when the outermost transaction has been committed.
Tests always run inside transactions, so this also introduces some logic to run callbacks once the test-wrapping transaction is reached.
* Adjustments to pass specs on Rails 6.0.0
* Use classic autoloader instead of Zeitwerk
* Update Rails 6.0.0 deprecated methods
* Rails 6.0.0 not allowing column with integer name
* Drop freedom_patches/rails6.rb
* Default value for trigger_transactional_callbacks? is true
* Bump rspec-rails version to 4.0.0.beta2
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
- Fixes deprecation regarding usage of BigDecimal in dev
- Handle edge case where query_hash would clear a non existent result
- Minor perf improvement to query_single
Most important thing though is that we are now on the latest gem
Introduce new patterns for direct sql that are safe and fast.
MiniSql is not prone to memory bloat that can happen with direct PG usage.
It also has an extremely fast materializer and very a convenient API
- DB.exec(sql, *params) => runs sql returns row count
- DB.query(sql, *params) => runs sql returns usable objects (not a hash)
- DB.query_hash(sql, *params) => runs sql returns an array of hashes
- DB.query_single(sql, *params) => runs sql and returns a flat one dimensional array
- DB.build(sql) => returns a sql builder
See more at: https://github.com/discourse/mini_sql
