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“MongoDB is dead. Long live Postgresql”

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Re: “MongoDB is dead. Long live Postgresql”

#91

Post by threeseed »

memracom wrote: post #36

Lets just say that PostgreSQL answers the criticisms of relational databases that led to NoSQL. The complaints all boiled down to saying that the RDBMS forced you to do things one way and that it was cumbersome. PostgreSQL evolved and fixed the most annoying issues like JSON support and schemaless key-value store support. That's the way open source is supposed to work. Now folks are learning that throwing out the bab…

PostgreSQL doesn't answer the criticisms of relational databases.

It is still cumbersome to use, hard to shard, even harder to cluster and is incredibly complex to manage compared to databases like Cassandra.

Re: “MongoDB is dead. Long live Postgresql”

#92

Post by remon »

efuquen wrote: post #69
remon wrote: post #63

Earlier quoted context omitted.

Although it is true that MongoDB uses a lot of disk compared to your average RDMS there are reasons for that. 1) MongoDB (and various other NoSQL solution) are schemaless and thus have to store document fields along with the values for each document. This alone usually results in roughly twice as much actual disk space being used compared to an RDBMS. 2) MongoDB preallocates fairly large chunks of disk for their mmap…

"Small note on the mmap thing; a lot of people consider the mmap based storage engine a big issue (I tend to agree)." This. Aside from general reliability issues I've had in the past, which are definitely fixable and might be now, this design decision is the thing that will cripple, and continue to cripple the db. The idea that some how the kernel is going to better at managing a db's memory is ridiculous. Kernel pag…

Why "continue to cripple"? It's actually one of the things that can be changed quite easily at some point in time and doesn't introduce insurmountable backwards compatibility issues. And as I mentioned (and you cut out of your quote) there is at least one alternative available already.

Re: “MongoDB is dead. Long live Postgresql”

#93

Post by eonil »

felideon wrote: post #87
spellboots wrote: post #61

Earlier quoted context omitted.

I disagree, I think that opening an issue on github is a good way to start a discussion about a feature. Many projects accept feature requests this way and if anyone did the same for one of my projects, this would be the way I would prefer them to handle it.

The thing is it sounds like he is just promoting his own fork he started 11 months ago, rather than "starting a discussion." > We suggest to put errbit on PG. For those who want to try - the code here: https://github.com/Undev/errbit/tree/pg-upstream The problem here is that the bad English grammar could have given the wrong impression. Maybe he is just saying: "hey guys, you should consider migrating to postgresql.…

It seems that latter one is far better description of how people feels.

Re: “MongoDB is dead. Long live Postgresql”

#94

Post by remon »

threeseed wrote: post #91
memracom wrote: post #36

Lets just say that PostgreSQL answers the criticisms of relational databases that led to NoSQL. The complaints all boiled down to saying that the RDBMS forced you to do things one way and that it was cumbersome. PostgreSQL evolved and fixed the most annoying issues like JSON support and schemaless key-value store support. That's the way open source is supposed to work. Now folks are learning that throwing out the bab…

PostgreSQL doesn't answer the criticisms of relational databases. It is still cumbersome to use, hard to shard, even harder to cluster and is incredibly complex to manage compared to databases like Cassandra.

You had me until the "like Cassandra" bit ;) If there's one thing where Cassandra loses the battle with other NoSQL tech then cluster managements is probably it. Also, it's a bit unfair to compare RDBMSs with Cassandra. Clustering is inherently going to be more complicated for RDBMSs. Incidentally it's actually where I feel MongoDB deserves a bit of credit.

Re: “MongoDB is dead. Long live Postgresql”

#95

Post by eonil »

jcampbell1 wrote: post #18
seiji wrote: post #3

Earlier quoted context omitted.

PostgreSQL has native json support now. What else is missing? Just a protocol implementation? I'd love to see MongoDB give up and become a PostgreSQL consultancy. Everybody I talk to in the field has the exact same Mongo story: "We love JSON! We use JSON everywhere! We just wanted a DB with native JSON support. We didn't look at the implementation details. We only looked at their marketing. Now we wake up at 3am to f…

It is probably not as simple as "supports json now". Imagine if HN comments were stored as a JSON document: Client A: Read JSON. Client B: Read JSON. Client A: Append new comment to json document. Client B: Append new comment to json document. Client A: Save JSON Client B: Save JSON A's comment will get deleted. My understanding is that Mongo DB does have a way to append a record within a document, but Postgres does…

This is exactly what people call ACID TRANSACTION. Which completely lacked on Mongo. MySQL also lacked this, so people had to deal with data loss until they get InnoDB.

Next time you choose a database, always check the ACID compliance. It will make your life far easier.

Re: “MongoDB is dead. Long live Postgresql”

#96

Post by jwarkentin »

endijs wrote: post #65

I'm no MongoDB expert, but recently started to look into this db. Can anyone tell me (from experience, not from promo materials) - for which use cases MongoDB is good fit and for which ones it's not? It's clear that it can't fit for everyone. That's why it would be good to know in advance, for what it most likely to find and for what it's most likely not to fit.

Some things to consider:

http://www.sarahmei.com/blog/2013/11/11/why-you-should-never...

Re: “MongoDB is dead. Long live Postgresql”

#98

Post by [deleted] »

felideon wrote: post #87
spellboots wrote: post #61

Earlier quoted context omitted.

I disagree, I think that opening an issue on github is a good way to start a discussion about a feature. Many projects accept feature requests this way and if anyone did the same for one of my projects, this would be the way I would prefer them to handle it.

The thing is it sounds like he is just promoting his own fork he started 11 months ago, rather than "starting a discussion." > We suggest to put errbit on PG. For those who want to try - the code here: https://github.com/Undev/errbit/tree/pg-upstream The problem here is that the bad English grammar could have given the wrong impression. Maybe he is just saying: "hey guys, you should consider migrating to postgresql.…

[deleted]

Re: “MongoDB is dead. Long live Postgresql”

#99

Post by calinet6 »

felideon wrote: post #87
spellboots wrote: post #61

Earlier quoted context omitted.

I disagree, I think that opening an issue on github is a good way to start a discussion about a feature. Many projects accept feature requests this way and if anyone did the same for one of my projects, this would be the way I would prefer them to handle it.

The thing is it sounds like he is just promoting his own fork he started 11 months ago, rather than "starting a discussion." > We suggest to put errbit on PG. For those who want to try - the code here: https://github.com/Undev/errbit/tree/pg-upstream The problem here is that the bad English grammar could have given the wrong impression. Maybe he is just saying: "hey guys, you should consider migrating to postgresql.…

... after thouroughly testing it in production for 11 months and verifying that they had a point.

This is perfectly valid. A pull req might have been better, but this starts a discussion as well, and might prompt the project owner to say "Sounds great! Submit a pull request," or alternatively, "Sounds cool! We'll provide a link to your fork on our page." Both good.

Re: “MongoDB is dead. Long live Postgresql”

#100

Post by lucian1900 »

remon wrote: post #63
lucian1900 wrote: post #25

Earlier quoted context omitted.

Mongo's disk format is extremely wasteful, the database files are gigantic. That is a real problem and there is no way to compact this to anywhere near the size something like Postgres would have for the same data. Mongo is very bad at managing used memory. In fact it doesn't actually manage memory since it just mmaps its database file. It also touches disk much more often than would be reasonable, especially for how…

Although it is true that MongoDB uses a lot of disk compared to your average RDMS there are reasons for that. 1) MongoDB (and various other NoSQL solution) are schemaless and thus have to store document fields along with the values for each document. This alone usually results in roughly twice as much actual disk space being used compared to an RDBMS. 2) MongoDB preallocates fairly large chunks of disk for their mmap…

1. That's not necessarily the only possible implementation. It would be trivial to assign a number to each key and keep this map in the header of the db file.

2. That's not really the issue, I don't care about the size of small dbs. Large dbs have gigantic sizes.

3. That is absolutely abysmal, yes.

It doesn't just use 2x as much space as other dbs, in practice that can be up to 20-30x as much in bad cases. It's commonly at least 5x.

It really is absolutely terrible when compared to pretty much anything. It's slower than safer dbs that can do the same and more things. There is no selling point.

Just don't use it.

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