CODEWITHSUNDEEP
javaalgorithmcachingdata-structures
Chandra Manthina
Chandra Manthina

Reputation: 147

Multiple key and value pair search

we have a plan to cache DB table on application side (to avoid DB calls). Our cache is key & value pair implementation. If I use primary key (column1) as key and all other data as value, how can we execute below queries against cache?

select * from table where column1=?
select * from table where column2=? and column3=?
select * from table where column4=? and column5=? and column6=?

One simplest option is to build 3 caches as below.

(column1) --> Data
(column2+column3) --> Data
(column4+column5) --> Data

Any other better options?

Key points:

Upvotes: 1

Views: 366

Answers (2)

Neo M Hacker
Neo M Hacker

Reputation: 899

Looks like you want an in-memory cache. Guava has cool caches--you would need a LoadingCache.

Here is the link to LoadingCache

Basically, for your problem, the idea would be to have three LoadingCache. LoadingCache has a method that you should implement. The method tells loading cache given the input, how to get the data in case of a cache miss. So, the first time you access the loading cache for query1, there would be a cache miss. The loading cache would use the method you implemented (your classic DAO method) to get the data, put it in the cache, and return it to you. The next time you access it, it will be served from your in-memory guava cache.

So if you have three methods

Data getData(Column1 column)
Data getData(Column2 column2, Column3 column3)
Data getData(Column4 column4, Column5 column5, Column6 column6)

your three LoadingCache will call these methods from the load implementation you write. And that's it. I find it very clean and simple to get what you want.

Upvotes: 1

KayDK
KayDK

Reputation: 134

You mentioned that you have to cache millions of records. Thats quite a big number. I do not recommened you building your own caching framework, especially not based on simplistic datastructures such as HashMaps. I highly recommend Redis - Check at http://redis.io. Companies such as Twitter, Stackoverflow etc are using Redis for their caches.

Here is the live demonstration of Redis - http://try.redis.io

Upvotes: 1

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