On Tue, Nov 27, 2018 at 07:18:39PM -0500, Tom Lane wrote:
> * When wal_compression is enabled and a "hole" is removed from a full
> * page image, the page image is compressed using PGLZ compression.
>
> (BTW, is this trying to say that we don't apply compression if the page
> contains no hole? If so, why not?)
Compression can be applied on a page with or without a hole. What this
sentence means is that the equivalent of a double level of compression
can be applied on top of the hole being removed, if the hole can be
removed.
--
Michael