A question about innodb_adaptive_hash_index and INSERT BUFFER AND ADAPTIVE HASH INDEX in error log

[paul paul]

Hello,

I have a question about innodb_adaptive_hash_index and INSERT BUFFER AND ADAPTIVE HASH INDEX in error log.

My mysql version is 5.7.32-log and the result of script 'show variables like "innodb_adaptive_hash_index";' is innodb_adaptive_hash_index = OFF. Is it the default value of 5.7? Because innodb_adaptive_hash_index = OFF is not in /etc/my.cnf.

And when I checked the error log, I always found the content like below:

-------------------------------------
INSERT BUFFER AND ADAPTIVE HASH INDEX
-------------------------------------
Ibuf: size 1, free list len 226391, seg size 226393, 31754 merges
merged operations:
insert 93877, delete mark 1165694, delete 251416
discarded operations:
insert 0, delete mark 0, delete 0
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
Hash table size 6375023, node heap has 0 buffer(s)
0.00 hash searches/s, 8885.44 non-hash searches/s

What does it mean? innodb_adaptive_hash_index= ON?

Thank you very much!