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Never use MongoDB. Ever. It's a rule of thumb that hasn't led me astray yet. http://www.sarahmei.com/blog/2013/11/11/why-you-should-never-use-mongodb/ http:/

Never use MongoDB. Ever. It's a rule of thumb that hasn't led me astray yet. http://www.sarahmei.com/blog/2013/11/11/why-you-should-never-use-mongodb/ http://www.sarahmei.com/blog/2013/11/11/why-you-should-never...

dominotw 6y ago
> It's a rule of thumb that hasn't led me astray yet. How can you know if your decision is correct if you never use it in the first place. Isn't it like only implementing A version of A/B and concluding that not implementing B version was a good decision.
jcpst 6y ago
Meh. I read the article, and I agree with it. But that is not what you are saying. Don’t use it for relational data. Don’t use it as your primary data store. At the enterprise I work at, I’ve had success delivering features where data science would have some job that aggregates production data and dumps it to kafka. Then we’ll map it and dump it in mongo. Stick a .net core microservice on top for retrieval. Works great, has none of the problems mentioned in that article. Of course, this might not make sense if you’re not big enough to where you need kafka, kubernetes, etc But “Never use it” is certainly not good advice.
karmakaze 6y ago
This part is totally misguided. > What’s missing from MongoDB is a SQL-style join operation, which is the ability to write one query that mashes together the activity stream and all the users that the stream references. Because MongoDB doesn’t have this ability, you end up manually doing that mashup in your application code, instead. Even with a normalized relational database one wouldn't make a single query to return rows from a join of tables T1, T2, T3, etc when there are repeating relations such as the users in the social graph. This might be done sometimes paying for the duplication to save a network round trip, that's all and no different.
- debaserab2 6y ago
  A list of activities joined to users wouldn't be a problem for an RDBMS. I'm not sure what you mean by "repeating relations".
  - karmakaze 6y ago
    The deep relations (7-table join) example in the link is something I wouldn't do (including the repeated 'user' entities) with an RDBMS, given that I expect some elements of some tables to appear multiple times, that's a waste of I/O and hard to cache. > Users have friends, friends have posts, posts have comments and likes, each comment has one commenter and each like has one liker. I would likely gather all the instances of User id in each context (user, friend, commenter, and liker) and query it separately from the JOIN query. Depends on your data which way works out better on average/worst-cases.

dominotw 6y ago

> It's a rule of thumb that hasn't led me astray yet. How can you know if your decision is correct if you never use it in the first place. Isn't it like only implementing A version of A/B and concluding that not implementing B version was a good decision.

jcpst 6y ago

Meh. I read the article, and I agree with it. But that is not what you are saying. Don’t use it for relational data. Don’t use it as your primary data store. At the enterprise I work at, I’ve had success delivering features where data science would have some job that aggregates production data and dumps it to kafka. Then we’ll map it and dump it in mongo. Stick a .net core microservice on top for retrieval. Works great, has none of the problems mentioned in that article. Of course, this might not make sense if you’re not big enough to where you need kafka, kubernetes, etc But “Never use it” is certainly not good advice.

karmakaze 6y ago

This part is totally misguided. > What’s missing from MongoDB is a SQL-style join operation, which is the ability to write one query that mashes together the activity stream and all the users that the stream references. Because MongoDB doesn’t have this ability, you end up manually doing that mashup in your application code, instead. Even with a normalized relational database one wouldn't make a single query to return rows from a join of tables T1, T2, T3, etc when there are repeating relations such as the users in the social graph. This might be done sometimes paying for the duplication to save a network round trip, that's all and no different.

debaserab2 6y ago
A list of activities joined to users wouldn't be a problem for an RDBMS. I'm not sure what you mean by "repeating relations".
- karmakaze 6y ago
  The deep relations (7-table join) example in the link is something I wouldn't do (including the repeated 'user' entities) with an RDBMS, given that I expect some elements of some tables to appear multiple times, that's a waste of I/O and hard to cache. > Users have friends, friends have posts, posts have comments and likes, each comment has one commenter and each like has one liker. I would likely gather all the instances of User id in each context (user, friend, commenter, and liker) and query it separately from the JOIN query. Depends on your data which way works out better on average/worst-cases.