You Can’t Sacrifice Partition Tolerance (2010)
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You Can’t Sacrifice Partition Tolerance (2010)
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Re: You Can’t Sacrifice Partition Tolerance (2010)
#2Satan is confusing the world "Yield".
God is watching. NIggers will be punished.
Re: You Can’t Sacrifice Partition Tolerance (2010)
#3It's worth keeping in mind that viewing a system as CP or AP usually isn't nuanced enough: https://martin.kleppmann.com/2015/05/11/please-stop-calling-...
Re: You Can’t Sacrifice Partition Tolerance (2010)
#4Maybe I'm missing something, but it seems like this is basically just glossing over this part:
> Some systems cannot be partitioned. Single-node systems (e.g., a monolithic Oracle server with no replication) are incapable of experiencing a network partition. But practically speaking these are rare;
I'm not sure how the writer came to the conclusion that these systems are rare. The website I'm working on now has a single monolithic Postgres server, and the majority of systems I've worked on connected to single monolithic datastores, so at the very least these systems exist. These aren't particularly interesting examples, but when talking theoretically like with the CAP theorem, you don't get to just ignore the rare or uninteresting cases. These seem like relatively common examples of choosing CA.
Of course, when you try to shard such databases, you're going to run into serious problems.
I guess the claim I can credit to the author is that CA really really really means no partition tolerance. Even one network partition puts you in CP or AP territory. But I don't think that means CA stores don't exist.
It may be that I'm just not understanding things correctly, though; the CAP paper is definitely a challenging read for me.
Re: You Can’t Sacrifice Partition Tolerance (2010)
#5Maybe I'm missing something, but it seems like this is basically just glossing over this part: > Some systems cannot be partitioned. Single-node systems (e.g., a monolithic Oracle server with no replication) are incapable of experiencing a network partition. But practically speaking these are rare; I'm not sure how the writer came to the conclusion that these systems are rare. The website I'm working on now has a sin…
You skipped the second part of that. Unless your web application is running on the database server then you are no longer running single node, your web app and db server can become partitioned.
Re: You Can’t Sacrifice Partition Tolerance (2010)
#6Maybe I'm missing something, but it seems like this is basically just glossing over this part: > Some systems cannot be partitioned. Single-node systems (e.g., a monolithic Oracle server with no replication) are incapable of experiencing a network partition. But practically speaking these are rare; I'm not sure how the writer came to the conclusion that these systems are rare. The website I'm working on now has a sin…
If you read the next sentence he says
> But practically speaking these are rare; add remote clients to the monolithic Oracle server and you get a distributed system which can experience a network partition (e.g., the Oracle server becomes unavailable).
Re: You Can’t Sacrifice Partition Tolerance (2010)
#7Maybe I'm missing something, but it seems like this is basically just glossing over this part: > Some systems cannot be partitioned. Single-node systems (e.g., a monolithic Oracle server with no replication) are incapable of experiencing a network partition. But practically speaking these are rare; I'm not sure how the writer came to the conclusion that these systems are rare. The website I'm working on now has a sin…
You skipped the second part of that. Unless your web application is running on the database server then you are no longer running single node, your web app and db server can become partitioned.
Ah, okay, I didn't understand that next part correctly the first time. So that does account for why the author says such systems are rare.
But that doesn't really help me understand why CA can't exist. There are still systems that simply don't have network partitions. SQLite on the same phone as the app using it? As I said, it doesn't seem like we ignore the rare or uninteresting cases.
Re: You Can’t Sacrifice Partition Tolerance (2010)
#8Maybe I'm missing something, but it seems like this is basically just glossing over this part: > Some systems cannot be partitioned. Single-node systems (e.g., a monolithic Oracle server with no replication) are incapable of experiencing a network partition. But practically speaking these are rare; I'm not sure how the writer came to the conclusion that these systems are rare. The website I'm working on now has a sin…
You skipped the second part of that. Unless your web application is running on the database server then you are no longer running single node, your web app and db server can become partitioned.
Even if your web app and database are on the same server, you may experience partitions between the client and server.
Re: You Can’t Sacrifice Partition Tolerance (2010)
#9Maybe I'm missing something, but it seems like this is basically just glossing over this part: > Some systems cannot be partitioned. Single-node systems (e.g., a monolithic Oracle server with no replication) are incapable of experiencing a network partition. But practically speaking these are rare; I'm not sure how the writer came to the conclusion that these systems are rare. The website I'm working on now has a sin…
If you read the next sentence he says > But practically speaking these are rare; add remote clients to the monolithic Oracle server and you get a distributed system which can experience a network partition (e.g., the Oracle server becomes unavailable).
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Re: You Can’t Sacrifice Partition Tolerance (2010)
#10The implication derived from a trivial probability argument is misleading. Failures are correlated, so 1-(1-P)^n is an upper bound, firstly, but secondly and much more importantly, the value being computed is the wrong value. Failure of a node is not partition. To non-trivially partition a cluster of N nodes requires (N-2) failures, when the cluster is fully connected, for example (as e.g. on any bus network). Handling trival partition is, well, trivial, in some important senses.