On 8/17/16 9:46 PM, Stephen Frost wrote:
* Jim Nasby (jim.na...@bluetreble.com) wrote:
> https://wiki.postgresql.org/wiki/Binary_Replication_Tutorial does
> not specify -c for any of the rsync commands. That's maybe safe for
> WAL, but I don't think it's safe for any of the other uses, right?
> I'd like someone to confirm before I just change the page... my
> intention is to just stick -c in all the commands.
-c is only relevant when you are doing an incremental copy, but on a
quick look, all those rsync commands appear to be doing full copies?
You would want -c if you were taking a backup and then doing an update
of it using rsync. or something along those lines, as you can't really
trust rsync's time/size based comparison as it only has a 1 second level
granularity.
I don't think it's any great leap for someone to think they can use
those commands incrementally. It's certainly one of the first things you
think of when using rsync. AFAIK there's no downside at all to using -c
when it is a brand new copy, so I'm thinking we should just put it in
there, especially considering what the potential downside is.
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Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
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