Re: History of WAL_LEVEL (archive vs hot_standby)

shamccoy wrote
> Hello.  I've been doing some benchmarks on performance / size differences
> between actions when wal_level is set to either archive or hot_standby. 
> I'm not seeing a ton of difference.  I've read some posts about
> discussions as to whether this parameter should be simplified and remove
> or merge these 2 values.
> 
> I'd like to understand the historic reason between have the extra
> "hot_standby" value.  Was it to introduce replication and not disturb the
> already working "archive" value?  If I'm new to Postgres, is there any
> strategic reason to use "archive" at this point if replication is
> something I'll be using in the future?  I'm not seeing any downside to
> "hot_standby" unless I'm missing something fundamental.
> 
> Thanks,
> Shawn

There is a semantic difference in that "archive" is limited to "wal
shipping" to a dead-drop area for future PITR.  "hot_standby" implies that
the wal is being sent to another running system that is immediately reading
in the information to maintain an exact live copy of the master.

As I think both can be used for PITR I don't believe there is much downside,
technically or with resources, to using hot_standby instead of archive; but
I do not imagine it having any practical benefit either.

David J.





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