-----------------
-- STEP 1: CREATE and load table daily_minutes (only need to do this once)
-----------------
-- DROP table if it already exists
IF EXISTS (SELECT 1 FROM information_schema.tables
            WHERE table_name = 'daily_minutes')
  DROP TABLE daily_minutes;

CREATE TABLE daily_minutes
(minute_num INT, minute_ts TIME);

DECLARE @minute_num INT, @minute_ts TIME, @NTot INT;
 SELECT @minute_num  = 1, 
        @minute_ts = '00:00:00', -- start at 12AM
        @NTot = (60 * 24);       -- 1440 minutes in a day

-- Loop to INSERT a row for each minute
WHILE (@minute_num <= @NTot)
BEGIN
  INSERT INTO daily_minutes SELECT @minute_num, @minute_ts;
  SELECT @minute_num = @minute_num + 1;  -- increment by 1
  SELECT @minute_ts = DATEADD(minute, 1, @minute_ts);  -- increment by 1 minute
END;

-----------------
-- STEP 2: SQL to identify missing rows
-- (NOTE: Log table name = log_table, columns = serial, advance, log_ts)
-----------------
DECLARE 
  @log_day  DATETIME,  -- the day of the log rows
  @gap      INT;       -- allowed gap before/after each minute

SELECT
  @log_day = CONVERT(CHAR(10), getdate()-1, 120), -- yesterday 12AM
  @gap = 1; -- 1 second before or after


-- CTE includes rows for target minutes that DO exist in the log table
-- (DATEADDs allow for the before/after gap)
;WITH CTE AS
(
  SELECT DM.minute_num, DM.minute_ts, LT.serial, LT.average, LT.log_ts 
    FROM daily_minutes DM INNER JOIN log_table LT
         ON LT.[log_ts] BETWEEN DATEADD(s, -@gap, @log_day + DM.minute_ts)
                            AND DATEADD(s, +@gap, @log_day + DM.minute_ts)
)
-- Query returns rows for minutes that are NOT in CTE
SELECT (@log_day + DM.minute_ts) AS missed_target_ts,
       DM.minute_num             AS DM_minute_num,
       DM.minute_ts              AS DM_minute_ts
  FROM daily_minutes DM
 WHERE DM.minute_num 
       BETWEEN (SELECT MIN(minute_num) FROM CTE)
           AND (SELECT MAX(minute_num) FROM CTE)
   AND NOT EXISTS
       (SELECT 1 FROM CTE
         WHERE minute_num = DM.minute_num);