Evernote blog: WhySQL?

Does anyone have a link to a decent comparison between MySQL and PostgreSQL? I'm really wondering why so many people use MySQL, even though it supports a lot fewer SQL features than PostgreSQL.

Very interesting to see them bucking the trends, I love his closing line:<p>"But we’re relatively satisfied with sharded MySQL storage for Evernote user account metadata, even though that’s not going to win any style points from the cool kids."<p>Indeed, hipsters beware!

There are other reasons to choose NoSQL For example, when Craigslist was using mySql and they had to change their schema, it took MONTHS to facilitate the change across all their slaves. You can also have a mixed strategy of using both RDBMS and NoSQL to achieve consistency while being able to be flexible to architecture changes. Lastly- have you looked at total overal cost? Setting up a large cluster with mySql will have a large operational cost and it may not be partition tolerant so if the wrong servers go down, it may cascade to your whole data store.

It helps that they have a perfectly shardable product I guess.

tldr - it works, we don't care about "being cool"

Can anyone explain the following bit: "They’re cleanly partitioned into 20 million data separate data sets, one per user."<p>Does it mean they have a database per user? That can't be right is it?

I get where they're coming from, but I do find this to be a little smug :)<p>See, they haven't run into problems with their setup, as per, MySql 'just works' for them.<p>What would be interesting and educational (for me anyway) would be a situation where folks that ran into serious problems with their SQL setup despite doing the 'right things' persevered where conventional knowledge would have them switch to a NoSql solution.<p>tldr; Dog bites man article, would love to hear from someone that actually struggled with a SQL solution and soldiered on.

The notebook/note example is weak - in a nosql database you need to design your data structure appropriately to get the level of atomicity you require.<p>Storing an entire notebook in a single document would be the most obvious. I use postgres all the time and sql is great, but poo-pooing nosql because it wouldn't work with your relational structure is not the best idea. Also - I have found a hybrid between nosql (mongodb) and sql (postgres) is ideal - who says you need to use a single database?

If the replication is asynchronous then SQL databases are not durable. So the most important feature of SQL databases generally isn't one.

I can imagine that while Evernote has a lot of data to store, it doesn't have the massive amount of concurrent reads that might occur with an equally large web app. Do they publish numbers on read/write usage?

The biggest news to me was that they are using MySQL.

It's amazing how when you focus on proven (but supposedly boring or old) technology that just works, and works very well, you can devote a lot of other resources to the actual product and usability.<p>Maybe it's the 30 year old in me showing, but I'm sticking with the 'it just works' crowd. Until some other approach provides a staggeringly overwhelming reason to switch. I find scaling up with MySQL to be ridiculously easy, allowing me to focus my time elsewhere. Ram, bandwidth, and fast storage have gotten substantially cheaper in the last few years, making it that much easier and cost effective to throw hardware at scaling up. For 99.9% of the Web, those hardware resources are expanding in value much faster than traffic is increasing.<p>(It's understood other developers find it just as easy to take a different approach)

That was the worst "why we still use mysql"-post ever.

This article is very weak, they insist a lot on ACID, but those are completely orthogonal concepts from SQL. Most NoSQL products are ACID.<p>Also, the example itself is very weak as bitdiffusion below pointed out.