Skip to Content Skip to Search

module ActiveRecord::Relation::RecordFetchWarning

Public instance methods

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.

Source code GitHub
# File activerecord/lib/active_record/relation/record_fetch_warning.rb, line 19
def exec_queries

  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(";")}"

Definition files