Supports some small regions(table) can not be merge.

[nolouch]

Description

Sometimes, some regions are hot but not large, do not merge them can improve performance. we want to specify some regions(table) can not be merge.

Score

• 900

Mentor

• @nolouch

Recommended Skills

• Go

Learning Materials

• https://github.com/tikv/tikv/blob/master/docs/how-to/configure/region-merge.md

[sourcelliu]

/pick-up-challenge

[sre-bot]

@mantuliu pick up issue success

[sourcelliu]

@nolouch My idea is to add a configuration parameter: MergeHotRegionInterval, the default value is 24 hours.
Plan A : At each heartbeat of the region, a judgment logic is added. If the current region is hot, the last hot time of this reigion is stored in the memory. Maintain a map of hot regions or other data structures in memory. The merge scheduler adds a judgment condition to the region that needs to be merged, and determines whether the time when the region became hot last time is within the time range of MergeHotRegionInterval. If it is within this time range, this region will not be merged.

Plan B: Or add a field to the RegionInfo of core / region.go, indicating the time when the region was last marked as hot, and store the value of this new field to disk with the RegionInfo information.

What do you think of this ideas? Plan A does not store related hot region information to disk. Some hot regions may be merged by mistake during the process of pd master-slave switch. Plan B can store the last hot time to disk.

[sourcelliu]

/give-up-challenge

[sre-bot]

@mantuliu give up issue success

[nolouch]

Hi @mantuliu , are you still interested in solving this problem? We have encountered a situation where there is a small table with hot spots. After the split, we must prevent it from being merged.

[nolouch]

ongoing #3839 closed this one.