The document provides tips for optimizing memory usage when working with Redis. It recommends: 1) avoiding redundant data in objects; 2) using more efficient serialization formats like Protobuf instead of JSON; and 3) storing smaller strings and values together in hashes to reduce overhead. Additional tips include using intsets for numeric IDs in sets, HyperLogLog for cardinality counting, and bitmaps for access control flags. Redis configuration options like hash-max-ziplist-entries can be tweaked to further improve memory usage. For analysis, the redis-rdb-tools GitHub project is recommended.

1. Memory Optimization
Sripathi Krishnan, CTO, HashedIn Technologies

2. Copyright © 2017 HashedIn Technologies Pvt. Ltd.
- Ensure the objects don’t have redundant data
- Users have recommended products
- If you cache users, ensure
recommended_products is just a reference

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- Default serialization libraries are not
efficient
- Use Protobuf / Message Pack / Others
- JSON must be compressed

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- Keys in redis have lots of overheads
- For smaller strings, combine them into a larger
hash
- Tweak hash-max-ziplist-entries and
hash-max-ziplist-value appropriately

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- Objects are usually saved in hashmap, but the
keys are redundant if every object has the
same keys
- “NamedTuple”: store objects in a list instead
- “C like struct”: Use Redis Bitfield command to
store fixed length values in a single string

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- Sets in Redis are normally stored as HashTables
- But if they only contain integers/longs, they are
stored in memory-efficient “intsets”
- 10x or more memory reduction if your IDs are
numeric only

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- Count Objects? Use HyperLogLog
- Check for Existence? Use Bloom Filter
You won’t get exact results, but sometimes the
memory savings are worth it.

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- Redis Strings can be used as a giant bitmap
- You can set/unset/toggle individual bits
Useful for things like access control - can this user
perform that operation?

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- Sorted Sets are very expensive memory-wise
- Tweak zset-max-ziplist-entries and
zset-max-ziplist-value if you are using lots of
smaller sorted sets

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- Sorted Sets are very expensive memory-wise
- Tweak zset-max-ziplist-entries and
zset-max-ziplist-value if you are using lots of
smaller sorted sets

11. Copyright © 2017 HashedIn Technologies Pvt. Ltd.
Take the guess work out of your memory analysis.
https://github.com/sripathikrishnan/redis-rdb-tools