MENTAL MODEL · M0501

CQRS

DecideHigh supportDecision Science

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Version 1.0.0 · Updated 2026-07-30

CORE DEFINITION

Command Query Responsibility Segregation. It separates the channels for "modifying data" (write/command) and "reading data" (read/query) completely, because "read" and "write" have vastly different requirements in performance, security, and frequency.

SCAFFOLDING EFFECT

psychology

Reduce cognitive load

Decouple complexity. In management, separate the "decision-maker" (write state) from the "reporter/observer" (read state). Do not let reporting meetings become decision meetings; mixing the two leads to inefficiency.

anchor

Anchor fast decisions

Separate read and write models—write (command) emphasizes consistency and business rules, read (query) emphasizes performance and presentation; the two have different load characteristics, and after separation they can be independently scaled and optimized.

MINIMUM ACTION

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Practice this model in one real situation:

When the system has far more reads than writes or the read and write models differ greatly, split the read and write sides
the write side maintains the truth model, the read side builds dedicated views/projections
use events to synchronize the two sides.

Check to track your progress (stored locally)

Learning progress0%

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Source support: Explicit

link
en.wikipedia.orghttps://en.wikipedia.org/wiki/Command_Query_Responsibility_SegregationZH · Explicit
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