Re: jsonb format is pessimal for toast compression

* Peter Geoghegan (pg(at)heroku(dot)com) wrote:
> If there is to be any effort to make jsonb a more effective target for
> compression, I imagine that that would have to target redundancy
> between JSON documents. With idiomatic usage, we can expect plenty of
> it.

While I certainly agree, that's a rather different animal to address and
doesn't hold a lot of relevance to the current problem. Or, to put it
another way, I don't think anyone is going to be surprised that two rows
containing the same data (even if they're inserted in the same
transaction and have the same visibility information) are compressed
together in some fashion.

We've got a clear example of someone, quite reasonably, expecting their
JSONB object to be compressed using the normal TOAST mechanism, and
we're failing to do that in cases where it's actually a win to do so.
That's the focus of this discussion and what needs to be addressed
before 9.4 goes out.

Thanks,

Stephen