WEEK 09 · 2026.09.21-09.27 · WRITER GATE

Day 2 - FB Post Search FULL: deep dives, writes and privacy freshness

2026-09-22 · TUE · 补齐 FB Post Search deep dives：请求量、multi-keyword/phrase、写入风暴、存储优化、隐私与删除新鲜度。

中文深度讲义Staff Q&AGPT Live Mock证据验收

今日固定时间表

三个学习窗口必须保持 exactly 08:50-10:55, 14:30-16:15, 20:30-21:15。

08:50-09:1508:50-10:55 system design
Recall repair from Day 1: source of truth, index document, candidate retrieval, rank features.
09:15-10:0508:50-10:55 system design
Read every remaining FB Post Search live heading and level expectation with direct anchors.
10:05-10:3508:50-10:55 system design
Deep dive: high request volume, hot query cache, phrase query positions, like-event aggregation and storage tiering.
10:35-10:5508:50-10:55 system design
Follow-up: privacy/ACL/delete changes, stale derived state, reindex/backfill and recovery metrics.
14:30-16:15NeetCode Graphs
Three contiguous Graphs slots below; no other tag.
20:30-21:15Staff Q&A nodes 1-7, then record one spoken answer against the MP3 script.

算法模块

NeetCode Graphs, exactly three slots today, contiguous slots 4-6 of 21.

#Problem / modePatternInvariantBug riskTimeSpace
4Clone Graph
Graphs · NEW · 30m solve + 5m evidence		graph traversal with memoone cloned node per original node id/referencecreating duplicate clones during cyclesO(V+E)O(V)
5Connected Components
Graphs · NEW · 30m solve + 5m evidence		adjacency DFS or union-findcomponent count decreases only when two roots mergedouble-counting isolated nodesO(V+E)O(V+E)
6Graph Valid Tree
Graphs · NEW · 30m solve + 5m evidence		tree = connected and acyclicn-1 edges plus full connectivity is sufficientdetecting only cycles but not disconnected graphsO(V+E)O(V+E)

今日产出

必须交付FB Post Search complete FULL artifact set and one follow-up answer.
修复规则If privacy changes are treated as async-only, add query-time ACL/delete guard and leakage metric.

Hello Interview 精确目录

使用 live heading 的 original title 和 direct anchor。

项目Level精确 canonical sectionDispositionDay
FB Post Searchh6Approachrequired readingDay 2
FB Post Searchh5Challengesrequired readingDay 2
FB Post Searchh5Approachrequired readingDay 2
FB Post Searchh5Challengesrequired readingDay 2
FB Post Searchh2Potential Deep Divesdeep diveDay 2
FB Post Searchh31) How can we handle the large volume of requests from users?deep diveDay 2
FB Post Searchh5Approachdeep diveDay 2
FB Post Searchh6Approachdeep diveDay 2
FB Post Searchh32) How can we handle multi-keyword, phrase queries?deep diveDay 2
FB Post Searchh5Approachdeep diveDay 2
FB Post Searchh5Challengesdeep diveDay 2
FB Post Searchh5Approachdeep diveDay 2
FB Post Searchh5Challengesdeep diveDay 2
FB Post Searchh33) How can we address the large volume of writes?deep diveDay 2
FB Post Searchh4Post Creationdeep diveDay 2
FB Post Searchh4Like Eventdeep diveDay 2
FB Post Searchh6Approachdeep diveDay 2
FB Post Searchh6Challengesdeep diveDay 2
FB Post Searchh6Approachdeep diveDay 2
FB Post Searchh6Challengesdeep diveDay 2
FB Post Searchh34) How can we optimize storage of our system?deep diveDay 2
FB Post Searchh2What is Expected at Each Level?level expectationDay 2
FB Post Searchh3Mid-Levellevel expectationDay 2
FB Post Searchh3Seniorlevel expectationDay 2
FB Post Searchh3Staff+level expectationDay 2

DDIA 精确决策卡

Only DDIA Ch4 and Ch13 decision links are allowed.

DayProjectDecisionLink
Day 2FB Post Searchlarge write volume chooses update pipeline and refresh interval consciouslyhttps://ddia.vonng.com/ch4/#sec_storage_btree_lsm_comparison
Day 2FB Post Searchrebuild/search index as derived state, then swap safelyhttps://ddia.vonng.com/ch13/#id340

Artifacts

PDF is intentionally absent; Week 9 requires MP3 only for the FULL/TRANSFER scripts.

FB follow-up drill FB English recall outline
Local study materials
Detailed lecture notes, audio, recall scripts, PDFs, Staff Q&A, and mock packs are archived locally and are intentionally not published on this site.