text: #  -*- text -*-
  #
  #  main/postgresql/process-radacct.sql -- Schema extensions for processing radacct entries
  #
  #  $Id: 5b486170e3292541288b4afac08f2611d02e3a0d $
  
  --  ---------------------------------
  --  - Per-user data usage over time -
  --  ---------------------------------
  --
  --  An extension to the standard schema to hold per-user data usage statistics
  --  for arbitrary periods.
  --
  --  The data_usage_by_period table is populated by periodically calling the
  --  fr_new_data_usage_period stored procedure.
  --
  --  This table can be queried in various ways to produce reports of aggregate
  --  data use over time. For example, if the fr_new_data_usage_period SP is
  --  invoked one per day just after midnight, to produce usage data with daily
  --  granularity, then a reasonably accurate monthly bandwidth summary for a
  --  given user could be obtained by queriing this table with:
  --
  --      SELECT
  --          TO_CHAR(CURRENT_TIMESTAMP, 'YYYY-Month') AS month,
  --          TRUNC(SUM(acctinputoctets)/1000/1000/1000,9) AS gb_in,
  --          TRUNC(SUM(acctoutputoctets)/1000/1000/1000,9) AS gb_out
  --      FROM
  --          data_usage_by_period
  --      WHERE
  --          username='bob' AND
  --          period_end IS NOT NULL
  --      GROUP BY
  --          month;
  --
  --           month      |    gb_in    |    gb_out
  --      ----------------+-------------+--------------
  --       2019-July      | 5.782279231 | 50.545664824
  --       2019-August    | 4.230543344 | 48.523096424
  --       2019-September | 4.847360599 | 48.631835488
  --       2019-October   | 6.456763254 | 51.686231937
  --       2019-November  | 6.362537735 | 52.385710572
  --       2019-December  | 4.301524442 | 50.762240277
  --       2020-January   | 5.436280545 | 49.067775286
  --      (7 rows)
  --
  CREATE TABLE data_usage_by_period (
      username text,
      period_start timestamp with time zone,
      period_end timestamp with time zone,
      acctinputoctets bigint,
      acctoutputoctets bigint
  );
  ALTER TABLE data_usage_by_period ADD CONSTRAINT data_usage_by_period_pkey PRIMARY KEY (username, period_start);
  
  
  --
  --  Stored procedure that when run with some arbitrary frequency, say
  --  once per day by cron, will process the recent radacct entries to extract
  --  time-windowed data containing acct{input,output}octets ("data usage") per
  --  username, per period.
  --
  --  Each invocation will create new rows in the data_usage_by_period tables
  --  containing the data used by each user since the procedure was last invoked.
  --  The intervals do not need to be identical but care should be taken to
  --  ensure that the start/end of each period aligns well with any intended
  --  reporting intervals.
  --
  --  It can be invoked by running:
  --
  --      SELECT fr_new_data_usage_period();
  --
  --
  CREATE OR REPLACE FUNCTION fr_new_data_usage_period ()
  RETURNS void
  LANGUAGE plpgsql
  AS $$
  DECLARE v_start timestamp;
  DECLARE v_end timestamp;
  BEGIN
  
      SELECT COALESCE(MAX(period_start), TO_TIMESTAMP(0)) INTO v_start FROM data_usage_by_period;
      SELECT DATE_TRUNC('second',CURRENT_TIMESTAMP) INTO v_end;
  
      --
      -- Add the data usage for the sessions that were active in the current
      -- period to the table. Include all sessions that finished since the start
      -- of this period as well as those still ongoing.
      --
      INSERT INTO data_usage_by_period (username, period_start, period_end, acctinputoctets, acctoutputoctets)
      SELECT *
      FROM (
          SELECT
              username,
              v_start,
              v_end,
              SUM(acctinputoctets) AS acctinputoctets,
              SUM(acctoutputoctets) AS acctoutputoctets
          FROM
              radacct
          WHERE
              acctstoptime > v_start OR
              acctstoptime IS NULL
          GROUP BY
              username
      ) AS s
      ON CONFLICT ON CONSTRAINT data_usage_by_period_pkey
      DO UPDATE
          SET
              acctinputoctets = data_usage_by_period.acctinputoctets + EXCLUDED.acctinputoctets,
              acctoutputoctets = data_usage_by_period.acctoutputoctets + EXCLUDED.acctoutputoctets,
              period_end = v_end;
  
      --
      -- Create an open-ended "next period" for all ongoing sessions and carry a
      -- negative value of their data usage to avoid double-accounting when we
      -- process the next period. Their current data usage has already been
      -- allocated to the current and possibly previous periods.
      --
      INSERT INTO data_usage_by_period (username, period_start, period_end, acctinputoctets, acctoutputoctets)
      SELECT *
      FROM (
          SELECT
              username,
              v_end + INTERVAL '1 SECOND',
              NULL::timestamp,
              0 - SUM(acctinputoctets),
              0 - SUM(acctoutputoctets)
          FROM
              radacct
          WHERE
              acctstoptime IS NULL
          GROUP BY
              username
      ) AS s;
  
  END
  $$;
  