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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
(Nearly) full tickless operation in 3.10
It seems a truism that any product described by its adherents as 'revolutionary' isn't.
(Off the top of my head I'm having a hard time even trying to come up with any examples of revolutionary software changes - this is in part the reason why I think sw patents are fundamentally wrong.)
SCALE 8x: Relational vs. non-relational
Posted Mar 4, 2010 17:30 UTC (Thu) by iabervon (subscriber, #722)
When something claims to be revolutionary, the claim is generally really that its evolution has just made the revolutionary change available to people who want a system that works and don't want to redesign their application regularly to account for recent discoveries.
Posted Mar 8, 2010 0:32 UTC (Mon) by dmag (subscriber, #17775)
- Ability to just "add nodes" to help performance, without massive administration overhead. This is non-trivial: You need merkel trees, vector clocks, gossip protocols, etc. See Cassandra and Riak (and the Dynamo paper).
- Ability to answer queries quickly - The RDBMS has tons of overhead, such as query parsing, index selection, query optimization, etc. Some of the Key-Value stores can answer a query before an RDBMS is finished figuring out what the query is.
- Ability to forget about the database enforcing schema -- that's the application's domain. (In the old days, the database had to enforce constraints because it was the "integration point". Now every app has an API, so the database is only used by one app.)
- Ability to forget about writing to disk. Writing to disk means you have to run disk-based recovery (fsck, special recovery code, etc.) It's slow and especially useless in the cloud (on EC2, you can instantly loose your disk and you don't get it back). Instead, if you want HA, you should do replication with fail-over (in multiple data centers.)
- Ability to forget about consistency - It's *much* easier to achieve HA if you drop consistency. Consistency isn't always a business requirement. (See Amazon, see airline overbooking policies)
Posted Mar 12, 2010 0:54 UTC (Fri) by robert_s (subscriber, #42402)
Posted Mar 12, 2010 19:44 UTC (Fri) by dmag (subscriber, #17775)
No, I didn't mean that. I wouldn't want Postgres to add all of those features, because it would be lots of extra complexity to get some "simple" features.
I was pointing out some limitations of current systems (since most people are still in the denial stage, saying "what's wrong with the RDBMS?") The fundamental concept behind the NoSQL movement is "we need new tools in the toolbox", and there are a lot of "new tools" to explore.
Posted Mar 7, 2010 7:46 UTC (Sun) by njs (guest, #40338)
But yeah, it's like the old rule about fields whose name contains the word "science"...
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