Re: unlogged tables

On 4/13/15 7:32 PM, David G. Johnston wrote:​

That particular use-case would probably best be served with a separate
replication channel which pushes data files from the primary to the
slaves and allows for the slave to basically "rewrite" its existing
table by pointing to the newly supplied version.  Some kind of "CREATE
STATIC TABLE" and "PUSH STATIC TABLE TO {all | replica name}" command
combo...though ideally with less manual intervention...

You still have the same problem of knowing if someone has scribbled on the data since the last checkpoint.

There's been recent discussion of adding support for read-only tables. If we had those, we might be able to support something like...

INSERT INTO unlogged;
ALTER TABLE unlogged SET READ ONLY;
CHECKPOINT;
/* take backup */

This should be safe as long as we WAL log changes to read-only status (which presumably we would).

How much work that would entail though, I don't know.

Ultimately you still have to get the data over to the other machine anyway. ISTM it'd be a LOT more useful to look at ways to make the WAL logging of bulk inserts (and especially COPY into a known empty table) a lot more efficient.