55 lines
2.4 KiB
Ruby
55 lines
2.4 KiB
Ruby
# frozen_string_literal: true
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# For large tables, PostgreSQL can take a long time to count rows due to MVCC.
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# Implements:
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# - distinct batch counter
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# - ordinary batch counter
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# - sum batch counter
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# - average batch counter
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# Needs indexes on the column below to calculate max, min and range queries
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# For larger tables just set use higher batch_size with index optimization
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#
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# In order to not use a possible complex time consuming query when calculating min and max for batch_distinct_count
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# the start and finish can be sent specifically
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#
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# Grouped relations can be used as well. However, the preferred batch count should be around 10K because group by count is more expensive.
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#
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# See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/22705
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#
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# Examples:
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# extend ::Gitlab::Database::BatchCount
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# batch_count(User.active)
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# batch_count(::Clusters::Cluster.aws_installed.enabled, :cluster_id)
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# batch_count(Namespace.group(:type))
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# batch_distinct_count(::Project, :creator_id)
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# batch_distinct_count(::Project.aimed_for_deletion.service_desk_enabled.where(time_period), start: ::User.minimum(:id), finish: ::User.maximum(:id))
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# batch_distinct_count(Project.group(:visibility_level), :creator_id)
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# batch_sum(User, :sign_in_count)
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# batch_sum(Issue.group(:state_id), :weight))
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# batch_average(Ci::Pipeline, :duration)
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# batch_average(MergeTrain.group(:status), :duration)
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module Gitlab
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module Database
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module BatchCount
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def batch_count(relation, column = nil, batch_size: nil, start: nil, finish: nil)
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BatchCounter.new(relation, column: column).count(batch_size: batch_size, start: start, finish: finish)
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end
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def batch_distinct_count(relation, column = nil, batch_size: nil, start: nil, finish: nil)
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BatchCounter.new(relation, column: column).count(mode: :distinct, batch_size: batch_size, start: start, finish: finish)
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end
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def batch_sum(relation, column, batch_size: nil, start: nil, finish: nil)
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BatchCounter.new(relation, column: nil, operation: :sum, operation_args: [column]).count(batch_size: batch_size, start: start, finish: finish)
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end
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def batch_average(relation, column, batch_size: nil, start: nil, finish: nil)
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BatchCounter.new(relation, column: nil, operation: :average, operation_args: [column]).count(batch_size: batch_size, start: start, finish: finish)
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end
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class << self
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include BatchCount
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end
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end
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end
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end
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