CODEWITHSUNDEEP
mysqlcaching
Paulo
Paulo

Reputation: 538

sql caching disadvantage?

I have a web server with a lot of web sites with many database operations, and i am tryng sql caching as a way to improve the performance of my server.

In general, is there any disadvantage about sql caching in a common environment?

Thanks

Upvotes: 0

Views: 1043

Answers (3)

Munchai
Munchai

Reputation: 1

All the above points are valid. Invalidation of stale cache entries would be a key concern as well as syncing local cache across multiple servers. You may want to look into a grid cache (e.g. Hazelcast, mem-cache) and Heimdall Data. Heimdall acts as a transparent cache and provides invalidation logic built in. In summary, sql caching itself is a good thing to do. It increases performance and can buffer sql traffic away from the database allowing scaling benefits.

Upvotes: 0

Alan Geleynse
Alan Geleynse

Reputation: 25139

The main problem with caching in a normal environment is cache expiration and stale data.

If you invalidate your cache every time data changes, you could end up rarely or never hitting the cache.

If you try to invalidate just the part of the cache that is changed, you have extra processing time to determine what to invalidate.

If you do not invalidate the cache or have cache timers, you may end up with stale data.

Depending on your environment and your requirements, you need to pick which solution best meets your needs. Sometimes it is ok to have some stale data, and in other applications it is not.

Upvotes: 0

Ariejan
Ariejan

Reputation: 11069

Well, caching consumes RAM memory, so you'll need plenty of that.

I'm not sure about what caching mechanism SQL server employs, but it might be possible that your queries return stale data for some time.

Your best options of performance improvement is to load as much data into RAM as possible instead of caching.

Upvotes: 1

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