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# frozen_string_literal: true
class LooseForeignKeys::DeletedRecord < ApplicationRecord
extend SuppressCompositePrimaryKeyWarning
include PartitionedTable
partitioned_by :created_at, strategy: :monthly, retain_for: 3.months, retain_non_empty_partitions: true
scope :ordered_by_primary_keys, -> { order(:created_at, :deleted_table_name, :deleted_table_primary_key_value) }
def self.load_batch(batch_size)
ordered_by_primary_keys
.limit(batch_size)
.to_a
end
# Because the table has composite primary keys, the delete_all or delete methods are not going to work.
# This method implements deletion that benefits from the primary key index, example:
#
# > DELETE
# > FROM "loose_foreign_keys_deleted_records"
# > WHERE (created_at,
# > deleted_table_name,
# > deleted_table_primary_key_value) IN
# > (SELECT created_at::TIMESTAMP WITH TIME ZONE,
# > deleted_table_name,
# > deleted_table_primary_key_value
# > FROM (VALUES (LIST_OF_VALUES)) AS primary_key_values (created_at, deleted_table_name, deleted_table_primary_key_value))
def self.delete_records(records)
values = records.pluck(:created_at, :deleted_table_name, :deleted_table_primary_key_value)
primary_keys = connection.primary_keys(table_name).join(', ')
primary_keys_with_type_cast = [
Arel.sql('created_at::timestamp with time zone'),
Arel.sql('deleted_table_name'),
Arel.sql('deleted_table_primary_key_value')
]
value_list = Arel::Nodes::ValuesList.new(values)
# (SELECT primary keys FROM VALUES)
inner_query = Arel::SelectManager.new
inner_query.from("#{Arel::Nodes::Grouping.new([value_list]).as('primary_key_values').to_sql} (#{primary_keys})")
inner_query.projections = primary_keys_with_type_cast
where(Arel::Nodes::Grouping.new([Arel.sql(primary_keys)]).in(inner_query)).delete_all
end
end
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