Re: Setting pd_lower in GIN metapage

On Sun, Sep 24, 2017 at 2:25 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> Added and updated the comments for both btree and hash index patches.

I don't have real complaints about this patch, this looks fine to me.

+ * Currently, the advantage of setting pd_lower is in limited cases like
+ * during wal_consistency_checking or while logging for unlogged relation
+ * as for all other purposes, we initialize the metapage. Note, it also
+ * helps in page masking by allowing to mask unused space.
I would have reworked this comment a bit, say like that:
Setting pd_lower is useful for two cases which make use of WAL
compressibility even if the meta page is initialized at replay:
- Logging of init forks for unlogged relations.
- wal_consistency_checking logs extra full-page writes, and this
allows masking of the unused space of the page.

Now I often get complains that I suck at this exercise ;)
--
Michael