CODEWITHSUNDEEP
rubyhash
truly bs
truly bs

Reputation: 23

Can Ruby handle large hash objects

I want to compare two hashes. Each can have more than 20,000 objects.

I have the following questions:

Upvotes: 1

Views: 1110

Answers (2)

undur_gongor
undur_gongor

Reputation: 15954

The hashes themselves are fast and not bound to low limits. E.g. this does not even take a millisecond here (Ruby 1.9.2 on Windows):

irb(main):008:0> hash1 = (0...20000).inject({}) { | r, i | r[rand(100)*100000 + i] = rand; r } ; 23
=> 23
irb(main):009:0> hash2 = (0...20000).inject({}) { | r, i | r[rand(100)*100000 + i] = rand; r } ; 23
=> 23
irb(main):010:0> hash3 = hash1.dup ; 23
=> 23
irb(main):011:0> hash1 == hash2
=> false
irb(main):012:0> hash1 == hash3
=> true

Everything else depends on what you are stuffing into the hashes.

Upvotes: 4

Carl Zulauf
Carl Zulauf

Reputation: 39558

Rails is a framework and has little to do with object comparison. Ruby is certainly capable of comparing 20,000 objects, assuming they fit well into memory or you are comparing them in a batch process that limits how many are instantiated at any time.

If you are are talking about comparing 20,000 ActiveRecord objects in-memory you will probably run out of memory and may experience pretty slow results even if you don't. ActiveRecord is pretty heavy-weight and not the best tool for working with large numbers of objects. However, I don't know what these 20,000 objects are or exactly how you are comparing them, so maybe they don't have to all be in-memory simultaneously and a batch process could complete this in a time frame you find acceptable.

If these are simple objects in a simple ruby hash you can certainly iterate through them pretty quickly (though what is fast is completely dependent on what this is for). If your comparison logic is pretty simple it shouldn't be too time consuming, assuming each object in your first hash is compared to a single corresponding object in the second hash. If every object in hash 1 is compared to each of the 20,000 in hash 2 then your total comparisons (20,000 * 20,0000) are much larger and this might not be as fast as you need.

Upvotes: 2

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