Read concern vs write concern vs read preference?
Understand the concept
Read concern, write concern and read preference control different parts of consistency and availability. Read concern controls which data a read may observe, write concern controls required acknowledgement, and read preference chooses eligible replica members. Combining them deliberately matters when an application expects to read a recent write or survive failover.
Important ideas
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Read concern controls the visibility guarantees of reads.
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Write concern controls the required write acknowledgement and durability options.
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Read preference chooses where to read; secondary reads may be behind the primary.
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A secondary may be available but stale; sending reads there is not automatically safe for every business decision.
Can you explain it without the notes?
Read concern vs write concern vs read preference?
Use your own words. Explain an example and one limitation before checking the explanation.
Check your explanation
Read concern, write concern and read preference control different parts of consistency and availability. Read concern controls which data a read may observe, write concern controls required acknowledgement, and read preference chooses eligible replica members. Combining them deliberately matters when an application expects to read a recent write or survive failover.
Turn this concept into a clear answer.
- Name the guarantee the user needs before choosing a setting; routing, visibility and acknowledgement are not interchangeable.
Keep connecting the ideas.
Next lesson: Replication vs sharding: what is the difference?Adapted from 04_MONGODB_MONGOOSE.md · “Read concern vs write concern vs read preference?”. Examples are study fragments; framework behavior can depend on your version.