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>The right to be forgotten, becomes one of the hardest challenges because of data immutability. Apache Kafka does not support deleting records, and although som

>The right to be forgotten, becomes one of the hardest challenges because of data immutability. Apache Kafka does not support deleting records, and although some eventual deletion is supported, it requires This always seemed like an incredibly toxic decision to me. It's one that crops up in all sorts of systems, large and small. What, none of these people /ever/ foresaw the need to delete some data?

wiz21c 9y ago
It's not that simple. For example in my business, we may give some money to help someone "once in its life" (the law says so). Therefore, if the persons asks to be deleted, then we might not apply the law anymore because it'll mean we won't remember the decision... I think GDPR is a good thing, but at some point, in my business, those who write the laws will have to be aware of it (and the legal teams is miles away from the IT stuff, sadly).
- mclarke 9y ago
  GDPR has an exemption related to the legal requirement to process data that might cover this (and related) scenarios. > ...(unless) processing is necessary for compliance with a legal obligation to which the controller is subject;
  - erpellan 9y ago
    Does this mean that someone can game 1-time special offers by repeatedly signing up and then demanding to be forgotten? There's probably no legal obligation to enforce once-only cashback sign-up offers, so the right to be forgotten would presumably have to be followed.
    - closeparen 9y ago
      There is an exception category for “legitimate business interest” so we’ll probably have to wait and see what the courts have to say.
- tscs37 9y ago
  The GDPR offers exceptions to the right to erasure, this mostly includes legal compliance (banks) or in the interest of legal claims or when data cannot be easily deleted as individual record. It also does not affect any non-digital documents which aren't filed. This is all laid out very thoroughly in the legal documents relating to this.
  - wiz21c 9y ago
    I must recognize I didn't read the section about removal thoroughly. But I did read the articles about the "categories of data" which are the major pain point right now 'cos it forces you to, well, find appropriate categories of data. It's a very interesting thing to do but, in my organization, it leads to many loooong discussions :-)
Antwnis 9y ago
As everything in life, to gain something, you need to sacrifice something else. With RDBMS you get mutability; but to go 10x or 100x faster/larger you need to make hard decisions. HDFS, S3 and other systems have immutability in-built. Immutability is not bad per-se, as it give (some) assurance that data has not been tampered with, and although it could be implemented, the system cost could be significant. Stricking the right balance is the challenge
closeparen 9y ago
Where integrity matters, you never want data to be mutated with no trace. An audit trail is almost always needed - it’s not an extreme leap, then, to say “why don’t we just replay the audit trail to arrive at the current state?”
nemothekid 9y ago
>What, none of these people /ever/ foresaw the need to delete some data? It's a performance trade off, and not a very surprising one. Hard Disk Drives have always been known to never actually delete data (if you want the data gone, you overwrite it with 0s). It's not unimaginable that this performance trade-off found its way up the stack. And just like a regular HDD, you can forcibly delete the data, it's just a very expensive operation that isn't needed 95% of the time.
- Sir_Substance 9y ago
  >And just like a regular HDD, you can forcibly delete the data Except apparently not, because the linked article is literally saying it's not supported. I get wanting an audit trail, and I get wanting to not delete data if you don't have to for performance reasons, but neither of those things is the same as saying "it's literally not possible to delete stuff".
  - mcny 9y ago
    What is your thought on this? > Encrypt with a user specific key when the data enters the log. You can effectively delete all the user specific data by throwing the key away. No tracking down files or reprocessing necessary. from https://news.ycombinator.com/item?id=15847674 https://news.ycombinator.com/item?id=15847674
    - Sir_Substance 9y ago
      From a technical perspective, that seems like a sensible compromise to me.
  - nemothekid 9y ago
    >Except apparently not, because the linked article is literally saying it's not supported. I see your point, but you are mistaken (or you took the wrong impression from the article) - it is supported, you just wouldn't want to do it day-to-day, and for the context of the article it might as well not exist. In Kafka, if you want to forcibly delete the data, you could simply just force topic compaction after a delete. Depending on the size of your data, a regular delete could take hours, which would likely blow the resource usage on any decently sized deployment. I bring this up because a lot of shiny "BigData" databases use Log Structured Merge Trees, which are immutable and deletes are mostly "soft-deletes" until a "compaction".

wiz21c 9y ago

It's not that simple. For example in my business, we may give some money to help someone "once in its life" (the law says so). Therefore, if the persons asks to be deleted, then we might not apply the law anymore because it'll mean we won't remember the decision... I think GDPR is a good thing, but at some point, in my business, those who write the laws will have to be aware of it (and the legal teams is miles away from the IT stuff, sadly).

mclarke 9y ago
GDPR has an exemption related to the legal requirement to process data that might cover this (and related) scenarios. > ...(unless) processing is necessary for compliance with a legal obligation to which the controller is subject;
- erpellan 9y ago
  Does this mean that someone can game 1-time special offers by repeatedly signing up and then demanding to be forgotten? There's probably no legal obligation to enforce once-only cashback sign-up offers, so the right to be forgotten would presumably have to be followed.
  - closeparen 9y ago
    There is an exception category for “legitimate business interest” so we’ll probably have to wait and see what the courts have to say.
tscs37 9y ago
The GDPR offers exceptions to the right to erasure, this mostly includes legal compliance (banks) or in the interest of legal claims or when data cannot be easily deleted as individual record. It also does not affect any non-digital documents which aren't filed. This is all laid out very thoroughly in the legal documents relating to this.
- wiz21c 9y ago
  I must recognize I didn't read the section about removal thoroughly. But I did read the articles about the "categories of data" which are the major pain point right now 'cos it forces you to, well, find appropriate categories of data. It's a very interesting thing to do but, in my organization, it leads to many loooong discussions :-)

Antwnis 9y ago

As everything in life, to gain something, you need to sacrifice something else. With RDBMS you get mutability; but to go 10x or 100x faster/larger you need to make hard decisions. HDFS, S3 and other systems have immutability in-built. Immutability is not bad per-se, as it give (some) assurance that data has not been tampered with, and although it could be implemented, the system cost could be significant. Stricking the right balance is the challenge

closeparen 9y ago

Where integrity matters, you never want data to be mutated with no trace. An audit trail is almost always needed - it’s not an extreme leap, then, to say “why don’t we just replay the audit trail to arrive at the current state?”

nemothekid 9y ago

>What, none of these people /ever/ foresaw the need to delete some data? It's a performance trade off, and not a very surprising one. Hard Disk Drives have always been known to never actually delete data (if you want the data gone, you overwrite it with 0s). It's not unimaginable that this performance trade-off found its way up the stack. And just like a regular HDD, you can forcibly delete the data, it's just a very expensive operation that isn't needed 95% of the time.

Sir_Substance 9y ago
>And just like a regular HDD, you can forcibly delete the data Except apparently not, because the linked article is literally saying it's not supported. I get wanting an audit trail, and I get wanting to not delete data if you don't have to for performance reasons, but neither of those things is the same as saying "it's literally not possible to delete stuff".
- mcny 9y ago
  What is your thought on this? > Encrypt with a user specific key when the data enters the log. You can effectively delete all the user specific data by throwing the key away. No tracking down files or reprocessing necessary. from https://news.ycombinator.com/item?id=15847674 https://news.ycombinator.com/item?id=15847674
  - Sir_Substance 9y ago
    From a technical perspective, that seems like a sensible compromise to me.
- nemothekid 9y ago
  >Except apparently not, because the linked article is literally saying it's not supported. I see your point, but you are mistaken (or you took the wrong impression from the article) - it is supported, you just wouldn't want to do it day-to-day, and for the context of the article it might as well not exist. In Kafka, if you want to forcibly delete the data, you could simply just force topic compaction after a delete. Depending on the size of your data, a regular delete could take hours, which would likely blow the resource usage on any decently sized deployment. I bring this up because a lot of shiny "BigData" databases use Log Structured Merge Trees, which are immutable and deletes are mostly "soft-deletes" until a "compaction".