Re:12 Months with MongoDB
by megaman821 on Monday October 25, 2010 @07:24PM
(#1832092)
It is kind of odd that speed is the main motivation to switch from MySQL. Horizontal scaling is the usually given reason. From what I have seen Mongo achieves most of its speed by not using fsync by default. There were some slides floating around a while ago that showed Postgres at about the same speed by turning off fsync.
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I think you referred to this slide from PGCon 2010 http://www.pgcon.org/2010/schedule/attachments/141_PostgreSQ...
I remember reading that when the developer of Sphinx was benchmarking MySQL's fulltext searches at Craigslist, most of the time spent performing a query was spent in locks and mutexes. The actual query time was very fast, but the overhead was what killed performance.
From what I understand, Postgres doesn't (necessarily) have those kinds of locking issues, but MongoDB does let you fetch documents (especially hierarchies) in a much more simple manner, rather than fetching them via potentially complicated join queries.
Surely those locking issues go away if you use READ COMMITTED mode though, right?
A lot of people find MongoDB is faster for queries because they avoid a lot of joins.
You could run mysql with the memory storage engine and with our schema--which would require multiple outer joins OR subqueries--mongodb will still be much faster. So I think it's much more than an fsync issue.
If the multiple outer joins or subqueries are too slow you can always denormalise a bit, you don't have to give up on your SQL database if you don't want to.
Re:12 Months with MongoDB
by megaman821 on Monday October 25, 2010 @09:42PM
(#1832541)
I still think it is amazing the the free SQL databases don't have materialized views yet.
MySQL's deficiencies aren't inherent to SQL databases. Other databases have faster query parsers and better query planners. It seems that with all the time and money invested into NoSQL solutions, Postgres could be improved to the level of Oracle or DB2.
This comment, which I completely agree with, really depresses me. People really like competing with each other rather than working together to build awesome solutions (and users often even /encourage/ this behavior with a pro-competition bias). The idea that we now have a million "sort of crummy" storage solutions rather than a couple, or even one, really good one--and mostly due to superficial differences in syntax of usage or specification of deployment--makes me want to cry.