difference is that returns self, instead of an array with the deleted objects, so methods can be chained. See delete_all for more information. Note that because delete_all removes records by directly running an SQL query into the database, the updated_at column of the object is not changed.

Raised on attempt to save stale record. Record is stale when it’s being saved in another query after instantiation, for example, when two users edit the same wiki page and one starts editing and saves the page before the other. Read more about optimistic locking in ActiveRecord::Locking module documentation.

Perform any necessary initialization upon the newly-established @ raw_connection – this is the place to modify the adapter’s connection settings, run queries to configure any application-global “session” variables, etc. Implementations may assume this method will only be called while holding @lock (or from #initialize).

A hook which allows you to clean up any time, wrongly taken into account in views, like database querying time.

PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and requires that the ORDER BY include the distinct column.

Returns an ActiveStorage::Filename instance of the filename that can be queried for basename, extension, and a sanitized version of the filename that’s safe to use in URLs.

This is a thread locals registry for EXPLAIN. For example returns the collected queries local to the current thread.

AsynchronousQueryInsideTransactionError will be raised when attempting to perform an asynchronous query from inside a transaction

WhereChain objects act as placeholder for queries in which where does not have any parameter. In this case, where can be chained to return a new relation.

Queries the primary key column’s value. If the primary key is composite, all primary key column values must be queryable.

The list of columns names the model should ignore. Ignored columns won’t have attribute accessors defined, and won’t be referenced in SQL queries.

Returns a list of scopes that should be applied for this Reflection object when querying the database.

ConnectionFailed will be raised when the network connection to the database fails while sending a query or waiting for its result.

Computes asset path to public directory. Plugins and extensions can override this method to point to custom assets or generate digested paths or query strings.

Enable the query cache within the block if Active Record is configured. If it’s not, it will execute the given block.

Same as #count_by_sql but perform the query asynchronously and returns an ActiveRecord::Promise .

Same as #find_by_sql but perform the query asynchronously and returns an ActiveRecord::Promise .

In the simple case, MySQL allows us to place JOINs directly into the UPDATE query. However, this does not allow for LIMIT, OFFSET and ORDER. To support these, we must use a subquery.

Same as #minimum, but performs the query asynchronously and returns an ActiveRecord::Promise .

Same as #maximum, but performs the query asynchronously and returns an ActiveRecord::Promise .

Same as #average, but performs the query asynchronously and returns an ActiveRecord::Promise .

Generates all the attribute related methods for columns in the database accessors, mutators and query methods.

Disable the query cache within the block if Active Record is configured. If it’s not, it will execute the given block.

Same as #pluck, but performs the query asynchronously and returns an ActiveRecord::Promise .

Same as #count, but performs the query asynchronously and returns an ActiveRecord::Promise .

Same as #pick, but performs the query asynchronously and returns an ActiveRecord::Promise .

Same as #sum, but performs the query asynchronously and returns an ActiveRecord::Promise .

Same as #ids, but performs the query asynchronously and returns an ActiveRecord::Promise .

This is for clearing cache on the reflection. Useful for tests that need to compare SQL queries on associations.

Makes the adapter execute EXPLAIN for the tuples of queries and bindings. Returns a formatted string ready to be logged.