49 lines
1.6 KiB
Ruby
49 lines
1.6 KiB
Ruby
|
# For large tables, PostgreSQL can take a long time to count rows due to MVCC.
|
||
|
|
# We can optimize this by using the reltuples count as described in https://wiki.postgresql.org/wiki/Slow_Counting.
|
||
|
|
module Gitlab
|
||
|
|
module Database
|
||
|
|
module Count
|
||
|
|
CONNECTION_ERRORS =
|
||
|
|
if defined?(PG)
|
||
|
|
[
|
||
|
|
ActionView::Template::Error,
|
||
|
|
ActiveRecord::StatementInvalid,
|
||
|
|
PG::Error
|
||
|
|
].freeze
|
||
|
|
else
|
||
|
|
[
|
||
|
|
ActionView::Template::Error,
|
||
|
|
ActiveRecord::StatementInvalid
|
||
|
|
].freeze
|
||
|
|
end
|
||
|
|
|
||
|
|
def self.approximate_count(model)
|
||
|
|
return model.count unless Gitlab::Database.postgresql?
|
||
|
|
|
||
|
|
execute_estimate_if_updated_recently(model) || model.count
|
||
|
|
end
|
||
|
|
|
||
|
|
def self.execute_estimate_if_updated_recently(model)
|
||
|
|
ActiveRecord::Base.connection.select_value(postgresql_estimate_query(model)).to_i if reltuples_updated_recently?(model)
|
||
|
|
rescue *CONNECTION_ERRORS
|
||
|
|
end
|
||
|
|
|
||
|
|
def self.reltuples_updated_recently?(model)
|
||
|
|
time = "to_timestamp(#{1.hour.ago.to_i})"
|
||
|
|
query = <<~SQL
|
||
|
|
SELECT 1 FROM pg_stat_user_tables WHERE relname = '#{model.table_name}' AND
|
||
|
|
(last_vacuum > #{time} OR last_autovacuum > #{time} OR last_analyze > #{time} OR last_autoanalyze > #{time})
|
||
|
|
SQL
|
||
|
|
|
||
|
|
ActiveRecord::Base.connection.select_all(query).count > 0
|
||
|
|
rescue *CONNECTION_ERRORS
|
||
|
|
false
|
||
|
|
end
|
||
|
|
|
||
|
|
def self.postgresql_estimate_query(model)
|
||
|
|
"SELECT reltuples::bigint AS estimate FROM pg_class where relname = '#{model.table_name}'"
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|
||
|
|
end
|