Feature Request

Is your feature request related to a problem? Please describe:
The data size of TiFlash replica can be larger than TiKV in some cases. Because by default, the most data of TiKV (the highest layer) is compressed by zstd, while TiFlash only uses lz4. And normally, the compression ratio of zstd is 1.5 times that of lz4.

For TPCC, the data size of TiKV is 51 GB, while TiFlash is 53 GB (with logical split disabled).

Describe the feature you'd like:
Support compression algorithms with better compression ratios, like zstd. Maybe automatically choose the best algorithm for different dataset / columns.

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy: