Hello, I'm Maneshwar. I'm building git-lrc, a Micro AI code reviewer that runs on every commit. It is free and source-available on Github. Star git-lrc to help devs discover the project. Do give it a try and share your feedback for improving the project.
Mini-pages are central to Bf-Tree performance, but they cannot grow forever.
If every insert, update, and tombstone remained in memory indefinitely, insertion cost would increase and memory would fill with stale records.
Bf-Tree continuously reorganizes mini-pages through merges, copying, and eviction.
When Does a Mini-Page Merge?
The paper describes two situations where a mini-page is merged back into its leaf page:
- The mini-page becomes too large
- The mini-page becomes cold (rarely accessed)
Since records inside a mini-page remain sorted, insertion cost rises as it grows.
Mini-page size increases
512B → 1KB → 2KB → ...
Insertion overhead rises
When a mini-page exceeds roughly 2KB, Bf-Tree merges it with the leaf page and produces a larger 4KB mini-page mirroring the leaf.
The merge process is roughly:
Locate leaf page
↓
Check available space
↓
Split leaf if needed
↓
Merge mini-page records
↓
Discard old mini-page
The old memory can then be reused.
This keeps write buffering useful without letting mini-pages become expensive secondary indexes.
Copy-On-Access Prevents Hot Data From Being Evicted
Bf-Tree stores mini-pages in a circular buffer.
Suppose a mini-page is close to eviction but suddenly becomes active again.
Instead of keeping it in place:
Old mini-page
↓
Copy to buffer tail
↓
Mark old copy as tombstone
The frequently accessed mini-page effectively receives a second life.
Hot data moves away from eviction boundaries.
Cold data moves toward disk.
This resembles a lightweight cache promotion strategy.
Evicting Records Instead of Evicting Entire Pages
One interesting detail in the paper is that Bf-Tree can evict individual cold records.
Each record maintains a reference bit:
Accessed recently → keep
Not accessed → evict
During copy-on-access:
- Hot records remain in memory
- Cold cache records are discarded immediately
- Dirty records (insertions/tombstones) trigger merge with leaf pages
So a mini-page gradually evolves:
Before:
[A][B][C][D][E]
Only A and D are hot
After:
[A][D]
Memory becomes concentrated around active keys.
This is much finer-grained than traditional page caches, where an entire page often survives because one record is frequently accessed.
Leaf Splits Still Exist
Despite the redesign, Bf-Tree has not eliminated classic B-Tree behavior.
Leaf pages still split when full.
The difference is where inserts land first:
Traditional B-Tree:
Insert → Leaf page → Possible split
Bf-Tree:
Insert → Mini-page
↓
Merge/Evict
↓
Possible leaf split
A split happens later, after buffering absorbs multiple writes.
Remaining mini-page records are compared against the split key and distributed across new leaf pages.
This delays structural modification and reduces immediate disk work.
The Bigger Pattern
Across merges, copy-on-access, record eviction, and splits, Bf-Tree repeatedly applies the same idea:
Keep hot data close, push cold data out, and postpone expensive disk operations as long as possible.
Mini-pages are not just a cache—they behave more like a continuously self-cleaning write buffer.
AI agents write code fast. They also silently remove logic, change behavior, and introduce bugs -- without telling you. You often find out in production.
git-lrc fixes this. It hooks into git commit and reviews every diff before it lands. 60-second setup. Completely free.*
Any feedback or contributors are welcome! It's online, source-available, and ready for anyone to use.
⭐ Star it on GitHub:
AI agents write code fast. They also silently remove logic, change behavior, and introduce bugs -- without telling you. You often find out in production.
git-lrc fixes this. It hooks into git commit and reviews every diff before it lands. 60-second setup. Completely free.
See It In Action
See git-lrc catch serious security issues such as leaked credentials, expensive cloud operations, and sensitive material in log statements
git-lrc-intro-60s.mp4
Why
- 🤖 AI agents silently break things. Code removed. Logic changed. Edge cases gone. You won't notice until production.
- 🔍 Catch it before it ships. AI-powered inline comments show you exactly what changed and what looks wrong.
- 🔁 Build a…