5 ms·

You might want to read the Wikipedia definition, because you're technically mistaken. https://en.m.wikipedia.org/wiki/Backup https://en.m.wikipedia.org/wiki/Ba

by y4mi 7y ago

You might want to read the Wikipedia definition, because you're technically mistaken. https://en.m.wikipedia.org/wiki/Backup https://en.m.wikipedia.org/wiki/Backup

Eikon 7y ago
I'm not, you can't do backup without replicating data, hence, if you do backup, you are doing replication.
- y4mi 7y ago
  It can be, it just doesn't have to be Let's say a typical admin of a small shop wants to backup his postgres database. The first thing he'll use is probably pg_dumpall which he'll output to a storage. No replication involved. The backup is just a bunch of sql statements to recover the last known state of the database. It's a different kind of format however, which -by definition- isn't a replica anymore. (And this process has several caveat's-one of which is that it can produce unusable dumps in some rare cases and isn't complete. users, triggers etc aren't dumped iirc.. could be wrong there)
  - Eikon 7y ago
    > No replication involved. The backup is just a bunch of sql statements to recover the last known state of the database. You probably should look up the definition of “replication”.
    - deleted 7y ago
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  - ben509 7y ago
    > It's a different kind of format however, which -by definition- isn't a replica anymore. All non-trivial replication has to cross machine boundaries. To transmit to another machine, you have to use a serial format since there are no pointers on the wire. So insisting that a replica must be the same format prohibits the concept of replication in practice.
    - y4mi 7y ago
      So, that admin dumped his database but didn't know that the data was using a custom locale which makes recovery troublesome. How is it a copy if it can't recover the original in some cases? We're not talking about a compressed archive here, it's a (incomplete) step-by-step instruction to recreate the data. If anything out of norm happens, it's gonna fail-possibly silently.
      - ben509 7y ago
        > How is it a copy if it can't recover the original in some cases? Do you think a gun is not a gun if it sometimes jams? > We're not talking about a compressed archive here I think we have two camps. Mine is considering "copy", "backup", "replica" to be broad categories that are distinguished by simple mathematical or technical properties. For instance, I'd consider a device that copied a single bit to be "copying," even though it's arguably just a wire. The other camp has very specific products and tasks in mind. A replica is associated with distributed computing, while a backup is something a systems administrator makes as part of disaster recovery.
        y4mi 7y ago
        > Do you think a gun is not a gun if it sometimes jams? but a pgdump is like a step by step guide for building the gun, leaving out a lot of the process... how can you honestly call that a gun? but i guess we'll have to agree to disagree. which proves that it was a discussion we shouldn't have started i guess.
  - anarazel 7y ago
    > (And this process has several caveat's-one of which is that it can produce unusable dumps in some rare cases and isn't complete. users, triggers etc aren't dumped iirc.. could be wrong there) Triggers are dumped, users need pg_dumpall (as they live across multiple databases, same with tablespaces).
ben509 7y ago
That's a long article; please quote the part you're referring to so we're all looking at the same text. > a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event Since a "replica" is a copy, that seems technically correct.
- y4mi 7y ago
  all fruits are apples because apples are fruit, right?
  - ben509 7y ago
    Your definition claims "a backup is a copy." The original claim was "a backup is a replication of the live dataset, although, usually out of sync to be useful when the main dataset goes bad." The only thing that makes a replica special is that it's in sync. Once you add the caveat that it's out of sync, it's just a copy.
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by y4mi 7y ago

You might want to read the Wikipedia definition, because you're technically mistaken. https://en.m.wikipedia.org/wiki/Backup https://en.m.wikipedia.org/wiki/Backup

Eikon 7y ago

I'm not, you can't do backup without replicating data, hence, if you do backup, you are doing replication.

y4mi 7y ago
It can be, it just doesn't have to be Let's say a typical admin of a small shop wants to backup his postgres database. The first thing he'll use is probably pg_dumpall which he'll output to a storage. No replication involved. The backup is just a bunch of sql statements to recover the last known state of the database. It's a different kind of format however, which -by definition- isn't a replica anymore. (And this process has several caveat's-one of which is that it can produce unusable dumps in some rare cases and isn't complete. users, triggers etc aren't dumped iirc.. could be wrong there)
- Eikon 7y ago
  > No replication involved. The backup is just a bunch of sql statements to recover the last known state of the database. You probably should look up the definition of “replication”.
  - deleted 7y ago
    [deleted]
  - deleted 7y ago
    [deleted]
- ben509 7y ago
  > It's a different kind of format however, which -by definition- isn't a replica anymore. All non-trivial replication has to cross machine boundaries. To transmit to another machine, you have to use a serial format since there are no pointers on the wire. So insisting that a replica must be the same format prohibits the concept of replication in practice.
  - y4mi 7y ago
    So, that admin dumped his database but didn't know that the data was using a custom locale which makes recovery troublesome. How is it a copy if it can't recover the original in some cases? We're not talking about a compressed archive here, it's a (incomplete) step-by-step instruction to recreate the data. If anything out of norm happens, it's gonna fail-possibly silently.
    - ben509 7y ago
      > How is it a copy if it can't recover the original in some cases? Do you think a gun is not a gun if it sometimes jams? > We're not talking about a compressed archive here I think we have two camps. Mine is considering "copy", "backup", "replica" to be broad categories that are distinguished by simple mathematical or technical properties. For instance, I'd consider a device that copied a single bit to be "copying," even though it's arguably just a wire. The other camp has very specific products and tasks in mind. A replica is associated with distributed computing, while a backup is something a systems administrator makes as part of disaster recovery.
      - y4mi 7y ago
        > Do you think a gun is not a gun if it sometimes jams? but a pgdump is like a step by step guide for building the gun, leaving out a lot of the process... how can you honestly call that a gun? but i guess we'll have to agree to disagree. which proves that it was a discussion we shouldn't have started i guess.
- anarazel 7y ago
  > (And this process has several caveat's-one of which is that it can produce unusable dumps in some rare cases and isn't complete. users, triggers etc aren't dumped iirc.. could be wrong there) Triggers are dumped, users need pg_dumpall (as they live across multiple databases, same with tablespaces).

ben509 7y ago

That's a long article; please quote the part you're referring to so we're all looking at the same text. > a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event Since a "replica" is a copy, that seems technically correct.

y4mi 7y ago
all fruits are apples because apples are fruit, right?
- ben509 7y ago
  Your definition claims "a backup is a copy." The original claim was "a backup is a replication of the live dataset, although, usually out of sync to be useful when the main dataset goes bad." The only thing that makes a replica special is that it's in sync. Once you add the caveat that it's out of sync, it's just a copy.
  - deleted 7y ago
    [deleted]