Before long we will be seeing terabyte buffer_pools. Reloading such will be (1) time consuming, and (2) well into "diminishing returns".

Suggest a new feature that says "Reload the hottest N% of the buffer pool". This way, you could get the most useful pages (eg, upper-level nodes in indexes) reloaded without spending a lot of time on the "long tail".

+1

looks good maps to what mysql are doing in 5.7. I thought their tradeoff of setting innodb_buffer_pool_dump_pct=25 was good (but it looks like mariadb doesn't have this setting).

MariaDB 10.1 is based on InnoDB 5.6, I guess we'll probably have this feature (thanks for mentioning that it exists) in MariaDB 10.2 which will import InnoDB 5.7, without having to implement anything on MariaDB side.

Ported the innodb_buffer_pool_dump_pct variable. Patch wasn't intrusive (dumped buffer pool in different order) and also included io throttling (was in same upstream commit).

Default of innodb_buffer_pool_dump_pct is still 100% to map to existing 10.1 behaviour.

figured MDEV-7635 already has a request to change default values so keeping this MDEV as porting the innodb_buffer_pool_dump_pct feature

commit b63bf7368b4881789bef931f90d4719b358cf507
Author: Jan Lindström <jan.lindstrom@mariadb.com>
Date: Tue Dec 15 09:30:13 2015 +0200

MDEV-8923: port innodb_buffer_pool_dump_pct from MySQL

Backport pull request #125 from grooverdan/MDEV-8923_innodb_buffer_pool_dump_pct to 10.0

WL#6504 InnoDB buffer pool dump/load enchantments

This patch consists of two parts:

1. Dump only the hottest N% of the buffer pool(s)
2. Prevent hogging the server duing BP load

From MySQL - commit b409342c43ce2edb68807100a77001367c7e6b8e

Add testcases for innodb_buffer_pool_dump_pct_basic.

Part of the code authored by Daniel Black

thanks jplindst