Description:
After commit c17d86b, mysql performance appears to be degraded when executing the insert statement:
```
INSERT INTO eids(id, eid) VALUES (65536, 72004) ON DUPLICATE KEY UPDATE eid = 72004 ;
```
We tested it using mysqlslap with the following test statement:
```
./mysqlslap --concurrency=1 --iterations=1 --create-schema=test --query="$mysql_inst" -uroot -S $(pwd)/mysql.sock --number-of-queries=1000000
```
The result of the test statement is as follows (We ran the test five times):
Before c17d86b:
Average number of seconds to run all queries: 33.879 seconds
Average number of seconds to run all queries: 35.374 seconds
Average number of seconds to run all queries: 34.401 seconds
Average number of seconds to run all queries: 35.198 seconds
Average number of seconds to run all queries: 34.298 seconds
After c17d86b:
Average number of seconds to run all queries: 34.471 seconds
Average number of seconds to run all queries: 34.572 seconds
Average number of seconds to run all queries: 36.266 seconds
Average number of seconds to run all queries: 35.586 seconds
Average number of seconds to run all queries: 38.208 seconds
How to repeat:
Execute the query statement that we provided above.