Changelog category (leave one):

• Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Currently clickhouse directly downloads all remote files to the local cache (even if they are only read once), which will frequently cause IO of the local hard disk. In some scenarios, these IOs may not be necessary and may easily cause negative optimization. As shown in the figure below, when we run SSB Q1-Q4, the performance of the cache has caused negative optimization.

In response to the above problems, we record the data access trend (an LRU queue) within an access frame at the cache layer. Only frequently accessed cache blocks will be saved locally. As shown in the figure, the addition of control will not cause significant negative optimization, but the data with hot spots can still be cached locally.

The relevant threshold can be set in the configuration file (the threshold indicates how many times a certain piece of data is accessed before being cached, the default value is 0).

Information about CI checks: https://clickhouse.com/docs/en/development/continuous-integration/