class PgPartitionManager::Time
Public Class Methods
new(partition, start: Date.today, db: nil)
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# File lib/pg_partition_manager.rb, line 9 def initialize(partition, start: Date.today, db: nil) raise ArgumentError, "Period must be 'month', 'week', or 'day'" unless ["month", "week", "day"].include?(partition[:period]) @partition = partition @start = case partition[:period] when "month" start - start.day + 1 # First day of the current month when "week" start - (start.cwday - 1) # First calendar day of the current week when "day" start end @db = db || PG.connect(ENV["DATABASE_URL"]) end
process(partitions)
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A convenience method for doing all the maintenance for a list of partitions
# File lib/pg_partition_manager.rb, line 82 def self.process(partitions) partitions.each do |part| pm = new(part) pm.drop_tables pm.create_tables end end
Public Instance Methods
create_tables()
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Create tables to hold future data
# File lib/pg_partition_manager.rb, line 40 def create_tables schema, table = @partition[:parent_table].split(".") start = @start stop = period_end(start) # Note that this starts in the *current* period, so we start at 0 rather # than 1 for the range, to be sure the current period gets a table *and* # we make the number of desired future tables (0..(@partition[:premake] || 4)).map do |month| child_table = "#{schema}.#{table}_p#{start.to_s.tr("-", "_")}" @db.exec("create table if not exists #{child_table} partition of #{schema}.#{table} for values from ('#{start}') to ('#{stop}')") start = stop stop = period_end(start) child_table end end
drop_tables()
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Drop the tables that contain data that should be expired based on the retention period
# File lib/pg_partition_manager.rb, line 27 def drop_tables schema, table = @partition[:parent_table].split(".") table_suffix = retention.to_s.tr("-", "_") result = @db.exec("select nspname, relname from pg_class c inner join pg_namespace n on n.oid = c.relnamespace where nspname = '#{schema}' and relname like '#{table}_p%' and relkind = 'r' and relname < '#{table}_p#{table_suffix}' order by 1, 2") result.map do |row| child_table = "#{row["nspname"]}.#{row["relname"]}" @db.exec("drop table if exists #{child_table}") child_table end end
period_end(start)
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Return the begin and end dates for the next partition range
# File lib/pg_partition_manager.rb, line 70 def period_end(start) case @partition[:period] when "month" start >> 1 when "week" start + 7 when "day" start + 1 end end
retention()
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Return the date for the oldest table to keep, based on the retention setting
# File lib/pg_partition_manager.rb, line 58 def retention case @partition[:period] when "month" @start << @partition[:retain] || 6 # Default to 6 months when "week" @start - ((@partition[:retain] || 4) * 7) # Default to 4 weeks when "day" @start - (@partition[:retain] || 7) # Default to 7 days end end