When is "ACID" ACID? Rarely
bailis.org
When is "ACID" ACID? Rarely
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Re: When is "ACID" ACID? Rarely
#2Huh? You ought not be depending on the default isolation settings. If your workload needs serializability, set it. Most don't. CAP teaches us that ACID is a spectrum in a distributed system.
Re: When is "ACID" ACID? Rarely
#3Huh? You ought not be depending on the default isolation settings. If your workload needs serializability, set it. Most don't. CAP teaches us that ACID is a spectrum in a distributed system.
Did you read the post? First, it covers both default isolation and maximum available. Second, note that many databases (like Oracle 11g) don't actually give you serializable semantics at ANY setting. Third, most of these products are not distributed systems. Fourth, ACID is not a spectrum for distributed systems; it is basically impossible to apply without sacrificing availability. But that's perhaps not a big deal if our non-distributed DBs don't provide real ACID anyway.
The real issue here is that the database world is a cargo cult where ignorant people scream ACID to denigrate new technologies without noticing that most production databases aren't running with anything close to ACID and that major database vendors can't even support ACID.
Re: When is "ACID" ACID? Rarely
#4Huh? You ought not be depending on the default isolation settings. If your workload needs serializability, set it. Most don't. CAP teaches us that ACID is a spectrum in a distributed system.
[deleted]
Re: When is "ACID" ACID? Rarely
#5When I first read this headline, I thought it had to do with purity of a certain Swiss-made variety that left its mark on San Francisco (and surprisingly, Palo Alto---e.g. Jerry Garcia and Ken Kesey). My mistake
Re: When is "ACID" ACID? Rarely
#6Huh? You ought not be depending on the default isolation settings. If your workload needs serializability, set it. Most don't. CAP teaches us that ACID is a spectrum in a distributed system.
Did you read the post? First, it covers both default isolation and maximum available. Second, note that many databases (like Oracle 11g) don't actually give you serializable semantics at ANY setting. Third, most of these products are not distributed systems. Fourth, ACID is not a spectrum for distributed systems; it is basically impossible to apply without sacrificing availability. But that's perhaps not a big deal i…
I did read the post.
It does cover both default and maximum. I didn't dispute that. I called out the notion that anyone ought to be depending on the defaults in the first place, or that SERIALIZABLE as a default was a good choice.
Yes, many don't support SERIALIZABLE. Didn't contradict that either.
As to whether many of these are or aren't distributed systems:
Ingres - has replication.
Aerospike - distributed/fault tolerant/blah blah
Persistit - nope. appears to be a library.
Clustrix - clustered.
Greenplum - this is shared-nothing clustered postgres.
DB2 for zOS - i have no idea. let's call this one not distributed, for giggles.
Informix - same
MySQL - lots of replication and HA options
MemSQL - replicated
MSSQL - replication and federated query modes
Nuodb - cloud database management? looks distributed to me.
Oracle - dont they have RAC ?
Berkeley (x2) - dont know. probably not.
PostgreSQL - a few replication options
HANA - no idea. lets call it in your favor.
ScaleDB - clustered.
Volt - shared nothing clustering
That's a little over half, by my count. Certainly close to most.
"The real issue here is that the database world is a cargo cult where ignorant people scream ACID to denigrate new technologies without noticing that most production databases aren't running with anything close to ACID and that major database vendors can't even support ACID."
Some can't. Some do. I'm not screaming. My main message is this: Don't depend on defaults. They differ from vendor to vendor. Understand your workload and use the APPROPRIATE isolation for it.
( edited for formatting and clarity )
Re: When is "ACID" ACID? Rarely
#7I think it's great that someone is taking a detailed look at distinct isolation levels for different systems. It's also worth looking at distinct levels for atomicity, consistency, and durability. One could then define an overall "pH" level for systems.
I would take exception to Bailis' statement that "it is impossible to simultaneously achieve high availability and serializability." At FoundationDB, we do exactly that.
Stephen Pimentel
foundationdb.com
Re: When is "ACID" ACID? Rarely
#8Huh? You ought not be depending on the default isolation settings. If your workload needs serializability, set it. Most don't. CAP teaches us that ACID is a spectrum in a distributed system.
Did you read the post? First, it covers both default isolation and maximum available. Second, note that many databases (like Oracle 11g) don't actually give you serializable semantics at ANY setting. Third, most of these products are not distributed systems. Fourth, ACID is not a spectrum for distributed systems; it is basically impossible to apply without sacrificing availability. But that's perhaps not a big deal i…
People scream ACiD on NoSQL's because they fail the easier A, C, or D in various forms, not the harder I part. Having AC&D go a long way in ensuring data correctness.
Re: When is "ACID" ACID? Rarely
#9When I first read this headline, I thought it had to do with purity of a certain Swiss-made variety that left its mark on San Francisco (and surprisingly, Palo Alto---e.g. Jerry Garcia and Ken Kesey). My mistake
I should have known better, especially in the context of this website. Due to a recent conversation with a friend about ph balance and the acidity of various foods, I thought it was a discussion of the chemical properties of various substances. Extraneous context affecting my initial impression.
Re: When is "ACID" ACID? Rarely
#10I think it's great that someone is taking a detailed look at distinct isolation levels for different systems. It's also worth looking at distinct levels for atomicity, consistency, and durability. One could then define an overall "pH" level for systems. I would take exception to Bailis' statement that "it is impossible to simultaneously achieve high availability and serializability." At FoundationDB, we do exactly th…
I think it's rather clear that he's talking about high availability in the CAP sense, which is precisely the kind of availability FoundationDB (rightly) doesn't claim to achieve (http://foundationdb.com/#CAP).
BTW, the images are failing to load on that page for me.