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0 pointsthreeseed2y ago0 comments

MongoDB remains the 5th most popular database: https://db-engines.com/en/ranking

And there are four major reasons still to choose MongoDB over something like PostgreSQL.

a) PostgreSQL has terrible support for horizontal scalability. Nothing is built-in, proven or supported.

b) MongoDB has superior ability to manipulate and query the JSON.

c) MongoDB is significantly faster for document-attribute updates.

d) MongoDB has better tooling for those of us that prefer to manage our schema in the application layer.

0 comments

paulddraper2y ago

By the time you need to shard PostgreSQL (billions of records?), you have lots and lots of resources to overcome that difficulty, a la Notion.

lmm2y ago

If you want to be high-availability then you need sharding or something like it from day 1. There's still no first-class way of running PostgreSQL that doesn't give you at least a noticeable write outage from a single-machine failure.

hans_castorp2y ago

> If you want to be high-availability then you need sharding or something like it from day 1

Sharding has nothing to do with high-availability.

threeseedOP2y ago

You horizontally scale for high availability as well as scalability.

And primary-secondary failover in my experience is rarely without issues.

There is a reason almost every new database aims to be distributed from the beginning.

dikei2y ago

>> There is a reason almost every new database aims to be distributed from the beginning.

That's partly because you can't compete with the existing RDBMSs if you're single node: they are good enough already. Nobody will buy your database if you don't introduce something more novel than PostgreSQL, whether that novelty is worth it or not.

paulddraper2y ago

Primary-secondary is simple and robust. If I had a dollar for every time I saw split-brain clusters....

---

And to respond sibling comment about "noticeable" downtime....

Primary-secondary failover in <1m is very feasible. And each minute downtime is a mere 0.002% for the month.

Primary-secondary isn't what is hurting your availability.

1 more reply

throwaway29902y ago

a) not true b) not true c) not true d) not true e) a lot of people have no idea json support exists in PostgreSQL.

olavgg2y ago

Agreed, when you see the index size in Mongo vs PostgreSQL, you will quickly understand that a single PostgreSQL instance can outscale a huge Mongo cluster.

pjmlp2y ago

PostgreSQL isn't the only RDMS to chose from.

j / k navigate · click thread line to collapse

0 comments

paulddraper2y ago

By the time you need to shard PostgreSQL (billions of records?), you have lots and lots of resources to overcome that difficulty, a la Notion.

lmm2y ago

hans_castorp2y ago

> If you want to be high-availability then you need sharding or something like it from day 1

Sharding has nothing to do with high-availability.

threeseedOP2y ago

You horizontally scale for high availability as well as scalability.

And primary-secondary failover in my experience is rarely without issues.

There is a reason almost every new database aims to be distributed from the beginning.

dikei2y ago

>> There is a reason almost every new database aims to be distributed from the beginning.

paulddraper2y ago

Primary-secondary is simple and robust. If I had a dollar for every time I saw split-brain clusters....

---

And to respond sibling comment about "noticeable" downtime....

Primary-secondary failover in <1m is very feasible. And each minute downtime is a mere 0.002% for the month.

Primary-secondary isn't what is hurting your availability.

1 more reply

throwaway29902y ago

a) not true b) not true c) not true d) not true e) a lot of people have no idea json support exists in PostgreSQL.

olavgg2y ago

Agreed, when you see the index size in Mongo vs PostgreSQL, you will quickly understand that a single PostgreSQL instance can outscale a huge Mongo cluster.

pjmlp2y ago

PostgreSQL isn't the only RDMS to chose from.

j / k navigate · click thread line to collapse