Greetings, * Mark Kirkwood (mark.kirkw...@catalyst.net.nz) wrote: > On 26/02/19 5:41 PM, Stephen Frost wrote: > >* Mark Kirkwood (mark.kirkw...@catalyst.net.nz) wrote: > >>ISTM that the onus should be on the patch submitter to provide additions to > >>pg_basebackup that make it as painless as possible for those people *not* > >>using pgBackRest to continue making backups. Breaking this is just not > >>right. Submitting patches that mean that people *must* use pgBackRest is > >>also not right IMHO. > >I'm sorry that there's some confusion here- to be clear, no one is > >required to use pgBackRest. pg_basebackup works quite well and wouldn't > >be impacted by the changes proposed no this thread. The arguments > >against removing the exclusive backup feature don't have anything to do > >with pg_basebackup. > > Ah yes (checks pg_basbackup code), you are correct! Reading this thread I > thought I saw a comment to the effect that pg_basebackup was being broken, > hence the less than impressed post.
No, I don't see breaking pg_basebackup as ok, but I do have concerns about how it doesn't provide for any validation of the backup unless you use tar+gzip. Unlike with exclusive mode, at least you don't run the risk with pg_basebackup that a crash will mean that PG won't come back up without intervention. I can understand how the comments which you were responding to might have lead to that confusion. > Your relentless bashing of people doing their own backups and heavy > marketing of pgBackRest - unfortunately - made it easy for me to believe > that this was a possibility that you might see as ok. So - apologies for the > misunderstanding, however less marketing of your own product would avoid me > jumping to the wrong conclusion. As for my personal recommendations, if you go back far enough, you can see where I used to discuss how to use the exclusive API for doing backups with people, because maybe they didn't like the tools available at the time (I didn't, after all), but after seeing how many issues come from doing that and realizing how bad it is that things like our documented archive_command doesn't ensure that WAL is actually written out to disk, I realized why dedicated tools had been written and started to recommend that people pick one of the dedicated tools instead of writing their own (and I used to recommend the other solution like barman right alongside pgBackRest, and I still do make the generic recommendation at times that people not try to build their own backup tool) but then after seeing things like CIFS mounts happily throwing kernel errors while returning success on (obviously, actually failed) fsync() calls, resulting in corrupted backups that would silently be corrupt if restored from, I realized that having an actual manifest of all files backed up and their checksums wasn't a "nice to have" kind of feature for a backup tool but something critical to a backup solution (thankfully, David knew that right from the start and so it was always part of pgBackRest) and so I have a pretty hard time recommending solutions that don't have that these days. As for back to the main topic of this thread, do I hope that removing the exclusive backup mode will cause people to look at and consider existing, purpose-build, backup solutions for PG, rather than trying to update their one-off backup shell scripts? Yes, of course I do. Am I trying to sneak something in that's going to force them to use pgBackRest? No, of course not. Note that pg_basebackup, barman and pgBackRest have had support for the non-exclusive API since it was introduced (or, for barman, even before then if one installed the pgespresso extension, and pg_basebackup since it was written because it uses the replication protocol), and so does WAL-G (though I'm not sure exactly when it got it, or maybe it always had it), and pg_probackup (which appears to have gotten it in May 2017, less than a year after 9.6 was released), and even the shell-based pitery (which got it at some point before pg_probackup, it looks like, based on the commits). Considering there's at least *5* other backup tools which already support the non-exclusive API, all of which have done so since the non-exclusive mode was introduced or shortly after, I really have to question the angle of attack being used here which is claiming that this thread is motivated by a goal of forcing people to pgBackRest. The main group who would be impacted by the exclusive mode going away are those who aren't using an existing solution and who either didn't get the memo about exclusive mode being deprecated, or decided just to ignore it, and those are the installations which really do concern me the most because they're the highest risk for people ending up losing their data. Thanks! Stephen
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