Module: ActiveRecord::Relation::RecordFetchWarning

Included in:
ActiveRecord::Relation
Defined in:
lib/active_record/relation/record_fetch_warning.rb

Defined Under Namespace

Modules: QueryRegistry

Instance Method Summary collapse

Instance Method Details

#exec_queries ⇒ Object

Deprecated: subscribe to sql.active_record notifications and access the row count field to detect large result set sizes.

When this module is prepended to ActiveRecord::Relation and config.active_record.warn_on_records_fetched_greater_than is set to an integer, if the number of records a query returns is greater than the value of warn_on_records_fetched_greater_than, a warning is logged. This allows for the detection of queries that return a large number of records, which could cause memory bloat.

In most cases, fetching large number of records can be performed efficiently using the ActiveRecord::Batches methods. See ActiveRecord::Batches for more information.



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# File 'lib/active_record/relation/record_fetch_warning.rb', line 19

def exec_queries
  QueryRegistry.reset

  super.tap do |records|
    if model.logger && ActiveRecord.warn_on_records_fetched_greater_than
      if records.length > ActiveRecord.warn_on_records_fetched_greater_than
        model.logger.warn "Query fetched #{records.size} #{@klass} records: #{QueryRegistry.queries.join(";")}"
      end
    end
  end
end