metrics: the number of oversized-region-count may changed frequently and can not be used as a reference.

[AndreMouche]

Bug Report

When the configuration of tikv instances in the cluster are not keep consistent,
the number of oversized-region-count may changed frequently and can not be used as a reference.

What did you do?

make the configuration region-max-size and region-max-keys not the same between tikv instances.

What did you expect to see?

I have no idea

What did you see instead?

the number of oversized-region-count may changed frequently and can not be used as a reference.

What version of PD are you using (pd-server -V)?

master

PD will randomly pull configuration from a TiKV and persist it locally(ref pd/server/cluster/cluster.go at release-8.1 · tikv/pd ).
If the configuration region-max-size and region-max-keys not the same between tikv instances, PD will pick the one it get recently and use it (region-max-size and region-max-keys) to determine if a region is oversized pd/pkg/core/region.go at 03488a478cd395d3bbbdc0a3f64abca5d69fcdc6 · tikv/pd , that is the root caused that the number of oversized regions changed frequently

Workaround: adjust the configuration region-max-size and region-max-keys of all tikv instances in the cluster to be consistent.

Impact: There is no specific impact on performance, but the number of oversized regions on region healthy cannot be used as a reference.

[seiya-annie]

/report customer