Exponential histogram

[knizhnik]

Problem

Current LFC size is specified based on sliding Hyper-log-log working set size estimation which doesn't take in account access frequency. For example there can be multiple OLTP queries working with most recent subset of theta and one slow OLAP query running in background which traverse all historical data. Currently working set size estimation will be the same as the whole database size.

Summary of changes

Use exponential histograms to calculate minimal cache size providing required hit ratio: hits/(hits + misses) relation.
For example with min hit ration 0.99, pages which access frequency is less than 1% of all accessed pages, will not be included in working set estimation

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[orca-security-us]

Orca Security Scan Summary

Status	Check	Issues by priority
Passed	Infrastructure as Code	0   0   0   0	View in Orca
Passed	Secrets	0   0   0   0	View in Orca
Passed	Vulnerabilities	0   0   0   0	View in Orca

[github-actions]

No tests were run or test report is not available

Test coverage report is not available

_{The comment gets automatically updated with the latest test results
b7015db at 2024-09-19T18:23:51.306Z :recycle:}