nodeJS, mongoDB, express, eJS - opinions on memory caching

Question

I'm building my first site using this framework, i'm remaking a website i had done in PHP+mySQL and wish to know something about performance... In my website, i have two kinds of content:

• Blog Posts (for 2 sections of the site) - these have the tendency to one day sum to thousands of records and, are more often updated
• Static (sort of) data: this is information i keep in the database, like site section's data (title, metatags, header image url, fixed html content, javascript and css filenames to include in that section), that is rarely updated and it's very small in size.

While i was learning the basics on nodeJS, i started thinking of a way to improve the performance of the website, in a way i couldn't do with PHP. So, what i'm doing is:

When i run the app, the static content is all loaded into memory, i have a "model" Object for each content that stores the data in an array, has a method to refresh that data, ie, when the administrator updates something, i call refresh() to go get the new data from the database to that array. In this way, for every page load, instead of querying the database, the app queries the object in memory directly.

What i would like to know is if there should be any increase of performance, working with objects directly in memory or if constant queries to the database would work just as good or even better.

Any documentation supporting your answer will be much appreciated.

Thanks

Answer 1

In terms of the general database performance, MongoDB will keep your working set in memory - that's its basic method of operation.

So, as long as there is no memory contention to cause the data to get swapped out, and it is not too large to fit into your physical RAM, then the queries to the database should be extremely fast (in the sub millisecond range once you have your data set paged in initially).

Of course, if the database is on a different host then you have network latency to think about and such, but theoretically you can treat them as the same until you have a reason to question it.

Answer 2

I don't think there will be any performance difference. First thing is that this static data is probably not so big (up to 100 records?) and querying DB for it is not a big deal. Second thing (more important) is that most DB engines (including mongoDB) have caching systems built-in (although I'm not sure how they work in details). Third thing is that holding query results in memory does not scale well (for big websites) unless you use storage engine like Redis. And that's my opinion, although I'm not the expert.