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In today’s article we will cover Querying Data Guard Apply Lag.
We can find out if there is an Apply Lag by querying the view below.
1 2 3 4 5 6 7 8 9 10 | SQL> set linesize 9000 SQL> col name format a10 SQL> SELECT * FROM V$STANDBY_EVENT_HISTOGRAM WHERE NAME = 'apply lag' AND COUNT > 0; NAME TIME UNIT COUNT LAST_TIME_UPDATED ---------- ---------- ---------------- ---------- -------------------- apply lag 0 seconds 1953 01/04/2017 09:53:09 apply lag 1 seconds 15 01/04/2017 09:50:33 apply lag 2 seconds 2 01/04/2017 09:36:53 apply lag 3 seconds 1 01/04/2017 09:30:03 |
From here it can be said that I have almost never experienced LAG.
If the highest number was 3-4-5 seconds instead of 0 seconds,
then I would have to work on whether this LAG was caused by CPU,
Network latency or Bandwith insufficiency.
