Which is funny because one of the things hosted Mongo will do is constantly send you automated emails suggesting that you should create indexes (for tables that MySQL or Postgres would laugh at)
Sends emails when scanned vs returned record ratio is greater than a threshold. Not quite sure how something like this would be different for MySQL/postgres. If an index is missing for you query pattern, wouldn't you create an index in MySQL/postgres?
> If an index is missing for you query pattern, wouldn't you create an index in MySQL/postgres?
No. I’d consider adding an index. An index is not free, it comes at a cost and that cost may well be higher than the costs of not having that index. For example, if a reporting query that runs once every few hours is lacking an index, the cost of updating that index on every write (and the disk space/memory used) may well exceed its benefits.
Exactly this. If you connect to your database and run a couple un-indexed queries to explore your data, any query which takes over 100ms will appear for the next 30 days in the "Performance Advisor" tab and it will offer you indexes to create targeted at that query. Just based on a query you did manually one time.
Just to note, this is referring to the features for a hosted databased on cloud.mongodb.com, and not something built into MongoDB the database.
I prefer this being shown in the slow queries over not showing it at all , from my experience from people running bad queries manually on production MySQL instances and starting a domino effect.
Secondary indicies can be a lot cheaper in a non-ACID database, where you can acknowledge a write when it is durably committed but index updates may not have completed.
My claim isn’t that indexes are a bad idea. The comment I replied to suggested that Mongo’s marketing targets people who don’t want to learn how to use indexes; my claim is that the reality of the hosted product is that it frequently suggests that you add indexes (presumably doing so helps with Mongo Corps hosting margins, as well as with performance [which is laughable even with indexes])
> my claim is that the reality of the hosted product is that it frequently suggests that you add indexes
But it auto-suggests what index to use and has a button for you to immediately apply it. I'd say it definitely intends for you to avoid learning how indexes in MongoDB work. The index suggestions it makes are often terrible.
> performance [which is laughable even with indexes]
It really depends on your use-case and how you can structure and query your data. For one such service I'm the lead on I haven't found anything faster that doesn't sacrifice the ability to do more generic queries when we occasionally need to. (Yes we've benchmarked against postgres json fields which is always everyone's first suggestion)
> But it auto-suggests what index to use and has a button for you to immediately apply it. I'd say it definitely intends for you to avoid learning how indexes in MongoDB work. The index suggestions it makes are often terrible.
Heh, yeah, you're right. So I guess it's the worst of both worlds: they try to not have you learn about indexes, but they give you terrible index suggestions, so when those don't work out you still end up having to learn about indexes :)
