What is measure of "Waits" value in AWR Report?

Question

Event
Waits
%Time -outs
Total Wait Time (s)
Avg wait (ms)
Waits /txn
SQL*Net more data from dblink
406,747
466
1
184.13
db file scattered read
28,659
330
12
12.97
SQL*Net message from dblink
30,115
254
8
13.63
log file parallel write
21,021
177
8
9.52
Hi All
    As below example, I have question What is measure of "Waits" value in "Wait Events" section in AWR report?
    Because "Waits" value is high but "Total Wait Time (s)" is low. example "SQL*Net message from dblink" has 30,115 "Waits" but "Total Wait Time (s)" less than "db file scattered read" has 28,659 "Waits".
    Could you please explain more about "Waits" value?
Thank you
Hiko

Answer 1

taohiko wrote:
Event
Waits
%Time -outs
Total Wait Time (s)
Avg wait (ms)
Waits /txn
SQL*Net more data from dblink
406,747
466
1
184.13
db file scattered read
28,659
330
12
12.97
SQL*Net message from dblink
30,115
254
8
13.63
log file parallel write
21,021
177
8
9.52
Hi All
    As below example, I have question What is measure of "Waits" value in "Wait Events" section in AWR report?
It's simply a count ... of the number of times the system had to "WAIT" on the specified event.
    Because "Waits" value is high but "Total Wait Time (s)" is low. example "SQL*Net message from dblink" has 30,115 "Waits" but "Total Wait Time (s)" less than "db file scattered read" has 28,659 "Waits".
Look at "AVG wait time".    In the one case, there were fewer occurrences of the event, but the average wait time per event was greater.
If I buy 3 hamburgers and pay $1000 each
or I buy 500 hamburgers and pay $1.00 each,
why do 3 hamburgers cost more than 500 hamburgers?
    Could you please explain more about "Waits" value?
"Waits" is the number of times the system had to wait on the named event, during the sampling period.
"Total Wait Time" is the total time (measured in seconds) spent waiting on all occurrences of the specified event, during the sampling period.
"Avg" wait" is the average time (measured in milliseconds) spent on each occurrence of the specified event, during the sampling period.
It seems pretty self-evident.  You count how many times something happens (waits), you measure the time spent doing that something (total wait time), and you divide the total time spent (total wait time) by the number of times it happened (waits) to find out the average time spent on each occurrence of that something.   
Thank you
Hiko