debian-mirror-gitlab/lib/gitlab/database/reindexing/index_selection.rb

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# frozen_string_literal: true
module Gitlab
module Database
module Reindexing
class IndexSelection
include Enumerable
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# Only reindex indexes with a relative bloat level (bloat estimate / size) higher than this
MINIMUM_RELATIVE_BLOAT = 0.2
# Only consider indexes with a total ondisk size in this range (before reindexing)
INDEX_SIZE_RANGE = (1.gigabyte..100.gigabyte).freeze
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delegate :each, to: :indexes
def initialize(candidates)
@candidates = candidates
end
private
attr_reader :candidates
def indexes
# This is an explicit N+1 query:
# Bloat estimates are generally available through a view
# for all indexes. However, estimating bloat for all
# indexes at once is an expensive operation. Therefore,
# we force a N+1 pattern here and estimate bloat on a per-index
# basis.
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@indexes ||= candidates
.not_recently_reindexed
.where(ondisk_size_bytes: INDEX_SIZE_RANGE)
.sort_by(&:relative_bloat_level) # forced N+1
.reverse
.select { |candidate| candidate.relative_bloat_level >= MINIMUM_RELATIVE_BLOAT }
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end
end
end
end
end