Method: ActiveRecord::PGExtensions::PostgreSQLAdapter#wal_lsn_diff

Defined in:
lib/active_record/pg_extensions/postgresql_adapter.rb

#wal_lsn_diff(lsn1 = :current, lsn2 = :last_replay) ⇒ Object

see www.postgresql.org/docs/current/functions-admin.html#id-1.5.8.33.5.5.2.2.4.1.1.1 lsns can be literals, or :current, :current_flush, :current_insert, :last_receive, or :last_replay

[View source]

221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
 
# File 'lib/active_record/pg_extensions/postgresql_adapter.rb', line 221

def wal_lsn_diff(lsn1 = :current, lsn2 = :last_replay)
  return nil unless wal?

  lsns = [lsn1, lsn2].map do |lsn|
    case lsn
    when :current then pre_pg10_wal_function_name("pg_current_wal_lsn()")
    when :current_flush then pre_pg10_wal_function_name("pg_current_flush_wal_lsn()")
    when :current_insert then pre_pg10_wal_function_name("pg_current_insert_wal_lsn()")
    when :last_receive then pre_pg10_wal_function_name("pg_last_wal_receive_lsn()")
    when :last_replay then pre_pg10_wal_function_name("pg_last_wal_replay_lsn()")
    else; quote(lsn)
    end
  end

  select_value("SELECT #{pre_pg10_wal_function_name("pg_wal_lsn_diff")}(#{lsns[0]}, #{lsns[1]})")
end