# learner

Published articles for learner.

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## 【etcd】运维与升级：member change、backup/restore 与 3.5-\>3.6/3.7 门

DevFeed: [【etcd】运维与升级：member change、backup/restore 与 3.5-\>3.6/3.7 门](<https://devfeed.tech/articles/etcd-member-change-backup-restore-3-5-3-6-3-7-33996.md>)

Original publisher: [Read original article](<https://quant67.com/post/etcd/14-ops-upgrade/14-ops-upgrade.html>)

Author: Liao Tonglang

Published: 2026-08-26T00:00:00Z

Content type: tutorial

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [etcd](<https://devfeed.tech/topics/etcd.md>), [upgrade](<https://devfeed.tech/topics/upgrade.md>), [Kubernetes](<https://devfeed.tech/topics/kubernetes.md>), [migration](<https://devfeed.tech/topics/migration.md>)

Tags: [backup](<https://devfeed.tech/tags/backup.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [learner](<https://devfeed.tech/tags/learner.md>), [member-change](<https://devfeed.tech/tags/member-change.md>), [migration](<https://devfeed.tech/tags/migration.md>), [operations](<https://devfeed.tech/tags/operations.md>), [raft](<https://devfeed.tech/tags/raft.md>), [recovery](<https://devfeed.tech/tags/recovery.md>), [restore](<https://devfeed.tech/tags/restore.md>), [snapshot](<https://devfeed.tech/tags/snapshot.md>), [upgrade](<https://devfeed.tech/tags/upgrade.md>), [v3](<https://devfeed.tech/tags/v3.md>), [v3-5](<https://devfeed.tech/tags/v3-5.md>), [v3-5-33](<https://devfeed.tech/tags/v3-5-33.md>), [v3-6](<https://devfeed.tech/tags/v3-6.md>), [v3-7](<https://devfeed.tech/tags/v3-7.md>)

### AI overview

A Chinese-language operational guide to etcd v3.5.33 covering member replacement and learner promotion, live snapshot backup and restore, Kubernetes control-plane recovery, patch upgrades, and documented upgrade gates from etcd 3.5 to 3.6 and 3.7.

### Source excerpt

member add/remove/replace 与 learner promote 检查单；snapshot backup/restore 及 K8s 语境 revision bump；3.5.33 补丁线与 3.6/3.7 官方升级门禁项，不超前写未钉 tag 能力。

## 【etcd】单 Raft 组与服务器角色：Leader、Follower、Learner 与 request 路由

DevFeed: [【etcd】单 Raft 组与服务器角色：Leader、Follower、Learner 与 request 路由](<https://devfeed.tech/articles/etcd-raft-leader-follower-learner-request-33984.md>)

Original publisher: [Read original article](<https://quant67.com/post/etcd/02-single-raft/02-single-raft.html>)

Author: Liao Tonglang

Published: 2026-08-26T00:00:00Z

Content type: article

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [etcd](<https://devfeed.tech/topics/etcd.md>), [Raft](<https://devfeed.tech/topics/raft.md>), [gRPC](<https://devfeed.tech/topics/grpc.md>)

Tags: [apiserver](<https://devfeed.tech/tags/apiserver.md>), [apply](<https://devfeed.tech/tags/apply.md>), [atomic](<https://devfeed.tech/tags/atomic.md>), [commit](<https://devfeed.tech/tags/commit.md>), [compaction](<https://devfeed.tech/tags/compaction.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [etcdserver](<https://devfeed.tech/tags/etcdserver.md>), [follower](<https://devfeed.tech/tags/follower.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [leader](<https://devfeed.tech/tags/leader.md>), [learner](<https://devfeed.tech/tags/learner.md>), [linearizable](<https://devfeed.tech/tags/linearizable.md>), [raft](<https://devfeed.tech/tags/raft.md>), [request](<https://devfeed.tech/tags/request.md>), [single-raft-group](<https://devfeed.tech/tags/single-raft-group.md>), [v3](<https://devfeed.tech/tags/v3.md>), [v3-5](<https://devfeed.tech/tags/v3-5.md>), [v3-5-33](<https://devfeed.tech/tags/v3-5-33.md>), [wal](<https://devfeed.tech/tags/wal.md>), [watch](<https://devfeed.tech/tags/watch.md>)

### AI overview

This article explains how etcd v3.5.33 embeds a single Raft group, separates EtcdServer responsibilities from the Raft library, and routes requests across Leader, Follower, and Learner roles. It covers gRPC write forwarding, linearizable and serializable reads, and the handling of watch, lease, and mutating requests.

### Source excerpt

钉清 etcd v3.5.33 单 Raft 组拓扑、EtcdServer 与 go.etcd.io/raft/v3 边界、Leader/Follower/Learner 角色及 gRPC 写读路由；与 distributed/13 分工。

## 【TiKV / HTAP 内核】Region - Multi-Raft - PD - Percolator - TiFlash

DevFeed: [【TiKV / HTAP 内核】Region - Multi-Raft - PD - Percolator - TiFlash](<https://devfeed.tech/articles/tikv-htap-region-multi-raft-pd-percolator-tiflash-33977.md>)

Original publisher: [Read original article](<https://quant67.com/post/db/tikv-htap/index.html>)

Author: Liao Tonglang

Published: 2026-07-16T00:00:00Z

Content type: article

Language: zh

Sources: [土法炼钢 - 系统与基础设施](<https://devfeed.tech/sources/source-4.md>)

Topics: [Raft](<https://devfeed.tech/topics/raft.md>), [rocksdb](<https://devfeed.tech/topics/rocksdb.md>), [etcd](<https://devfeed.tech/topics/etcd.md>), [SQL](<https://devfeed.tech/topics/sql.md>), [CockroachDB](<https://devfeed.tech/topics/cockroachdb.md>), [Databases](<https://devfeed.tech/topics/databases.md>)

Tags: [database](<https://devfeed.tech/tags/database.md>), [distributed](<https://devfeed.tech/tags/distributed.md>), [distributed-kv](<https://devfeed.tech/tags/distributed-kv.md>), [etcd](<https://devfeed.tech/tags/etcd.md>), [htap](<https://devfeed.tech/tags/htap.md>), [learner](<https://devfeed.tech/tags/learner.md>), [multi-raft](<https://devfeed.tech/tags/multi-raft.md>), [pd](<https://devfeed.tech/tags/pd.md>), [percolator](<https://devfeed.tech/tags/percolator.md>), [raft](<https://devfeed.tech/tags/raft.md>), [range](<https://devfeed.tech/tags/range.md>), [region](<https://devfeed.tech/tags/region.md>), [rocksdb](<https://devfeed.tech/tags/rocksdb.md>), [snapshot](<https://devfeed.tech/tags/snapshot.md>), [split](<https://devfeed.tech/tags/split.md>), [sql](<https://devfeed.tech/tags/sql.md>), [storage](<https://devfeed.tech/tags/storage.md>), [tidb](<https://devfeed.tech/tags/tidb.md>), [tiflash](<https://devfeed.tech/tags/tiflash.md>), [tikv](<https://devfeed.tech/tags/tikv.md>), [tso](<https://devfeed.tech/tags/tso.md>)

### AI overview

This article series explains TiKV 7.x/8.x internals through Region modeling, Multi-Raft replication, raftstore apply, RocksDB column families, PD and TSO scheduling, Percolator transactions, coprocessor boundaries, and TiFlash Learner freshness. It also compares selected aspects with etcd and CockroachDB.

### Source excerpt

补齐 RocksDB 单 Region、Raft 协议与 HTAP 范式之间的工程链路：以 TiKV 7.x/8.x 拆解 Region、Multi-Raft、raftstore、PD/TSO 与 Percolator 事务，并以 TiFlash Learner 收束新鲜度；CockroachDB 对照与选型。

## Weak Learning, Boosting, and the AdaBoost algorithm

DevFeed: [Weak Learning, Boosting, and the AdaBoost algorithm](<https://devfeed.tech/articles/weak-learning-boosting-and-the-adaboost-algorithm-40383.md>)

Original publisher: [Read original article](<https://www.jeremykun.com/2015/05/18/boosting-census/>)

Published: 2015-05-18T09:00:00Z

Content type: tutorial

Language: en

Sources: [Jeremy Kun](<https://devfeed.tech/sources/jeremy-kun.md>)

Topics: [Algorithm](<https://devfeed.tech/topics/algorithm.md>), [Learning](<https://devfeed.tech/topics/learning.md>)

Tags: [algorithm](<https://devfeed.tech/tags/algorithm.md>), [better](<https://devfeed.tech/tags/better.md>), [boosting](<https://devfeed.tech/tags/boosting.md>), [classification](<https://devfeed.tech/tags/classification.md>), [distribution](<https://devfeed.tech/tags/distribution.md>), [efficiently](<https://devfeed.tech/tags/efficiently.md>), [function](<https://devfeed.tech/tags/function.md>), [learner](<https://devfeed.tech/tags/learner.md>), [learning](<https://devfeed.tech/tags/learning.md>), [models](<https://devfeed.tech/tags/models.md>), [number](<https://devfeed.tech/tags/number.md>), [pac-learning](<https://devfeed.tech/tags/pac-learning.md>), [re](<https://devfeed.tech/tags/re.md>), [runtime](<https://devfeed.tech/tags/runtime.md>)

### AI overview

This article introduces learning models in the context of Probably Approximately Correct (PAC) learning and compares the usual PAC model with weak PAC learning. It explains that weak learning requires accuracy only slightly better than random guessing and states that weak and strong learning are equivalent.

### Source excerpt

When addressing the question of what it means for an algorithm to learn, one can imagine many different models, and there are quite a few. This invariably raises the question of which models are "the same" and which are "different," along with a precise description of how we're comparing models. We've seen one learning model so far, called Probably Approximately Correct (PAC), which espouses the following answer to the learning question: