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# frozen_string_literal: true
module Gitlab
module Database
module Partitioning
class SlidingListStrategy
attr_reader :model, :partitioning_key, :next_partition_if, :detach_partition_if
delegate :table_name, to: :model
def initialize(model, partitioning_key, next_partition_if:, detach_partition_if:)
@model = model
@partitioning_key = partitioning_key
@next_partition_if = next_partition_if
@detach_partition_if = detach_partition_if
ensure_partitioning_column_ignored!
end
def current_partitions
Gitlab::Database::PostgresPartition.for_parent_table(table_name).map do |partition|
SingleNumericListPartition.from_sql(table_name, partition.name, partition.condition)
end.sort
end
def missing_partitions
if no_partitions_exist?
[initial_partition]
elsif next_partition_if.call(active_partition.value)
[next_partition]
else
[]
end
end
def initial_partition
SingleNumericListPartition.new(table_name, 1)
end
def next_partition
SingleNumericListPartition.new(table_name, active_partition.value + 1)
end
def extra_partitions
possibly_extra = current_partitions[0...-1] # Never consider the most recent partition
extra = possibly_extra.take_while { |p| detach_partition_if.call(p.value) }
default_value = current_default_value
if extra.any? { |p| p.value == default_value }
Gitlab::AppLogger.error(message: "Inconsistent partition detected: partition with value #{current_default_value} should not be deleted because it's used as the default value.",
partition_number: current_default_value,
table_name: model.table_name)
extra = extra.reject { |p| p.value == default_value }
end
extra
end
def after_adding_partitions
active_value = active_partition.value
model.connection.change_column_default(model.table_name, partitioning_key, active_value)
end
def active_partition
# The current partitions list is sorted, so the last partition has the highest value
# This is the only partition that receives inserts.
current_partitions.last
end
def no_partitions_exist?
current_partitions.empty?
end
private
def current_default_value
column_name = model.connection.quote(partitioning_key)
table_name = model.connection.quote(model.table_name)
value = model.connection.select_value <<~SQL
SELECT columns.column_default AS default_value
FROM information_schema.columns columns
WHERE columns.column_name = #{column_name} AND columns.table_name = #{table_name}
SQL
raise "No default value found for the #{partitioning_key} column within #{model.name}" if value.nil?
Integer(value)
end
def ensure_partitioning_column_ignored!
unless model.ignored_columns.include?(partitioning_key.to_s)
raise "Add #{partitioning_key} to #{model.name}.ignored_columns to use it with SlidingListStrategy"
end
end
end
end
end
end
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