btree_gist's gist_inet_ops and gist_cidr_ops opclasses are
fundamentally broken: they rely on an approximate representation of
the inet values and hence sometimes miss rows they should return.
We want to eventually get rid of them altogether, but as the first
step on that journey, we should mark them not-opcdefault.
To do that, roll up the preceding deltas since 1.2 into a new base
script btree_gist--1.9.sql. This will allow installing 1.9 without
going through a transient situation where gist_inet_ops and
gist_cidr_ops are marked as opcdefault; trying to create them that
way will fail if there's already a matching default opclass in the
core system. Additionally provide btree_gist--1.8--1.9.sql, so
that a database that's been pg_upgraded from an older version can
be migrated to 1.9.
I noted along the way that commit 57e3c5160 had missed marking the
gist_bool_ops support functions as PARALLEL SAFE. While that probably
has little harmful effect (since AFAIK we don't check that when
calling index support functions), this seems like a good time to make
things consistent.
Readers will also note that I removed the former habit of installing
some opclass operators/functions with ALTER OPERATOR FAMILY, instead
just rolling them all into the CREATE OPERATOR CLASS steps. The
comment in btree_gist--1.2.sql that it's necessary to use ALTER for
pg_upgrade reproducibility has been obsolete since we invented the
amadjustmembers infrastructure. Nowadays, gistadjustmembers will
force all operators and non-required support functions to have "soft"
opfamily dependencies, regardless of whether they are installed by
CREATE or ALTER.
Author: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/2483812.1754072263@sss.pgh.pa.us
We can revert the code changes of commit b5febc1d1 now, because
commit 9a3ddeb51 installed a real solution for the difficulty
that b5febc1d1 just dodged, namely that the planner might pick
the wrong one of several index columns nominally containing the
same value. It only matters which one we pick if we pick one
that's not returnable, and that mistake is now foreclosed.
Although both of the aforementioned commits were back-patched,
I don't feel a need to take any risk by back-patching this one.
The cases that it improves are very corner-ish.
Discussion: https://postgr.es/m/3179992.1641150853@sss.pgh.pa.us
This reverts commit 9f984ba6d23dc6eecebf479ab1d3f2e550a4e9be.
It was making the buildfarm unhappy, apparently setting client_min_messages
in a regression test produces different output if log_statement='all'.
Another issue is that I now suspect the bit sortsupport function was in
fact not correct to call byteacmp(). Revert to investigate both of those
issues.
Commit b5febc1d1 added a contrib/btree_gist test case that has been
observed to fail in the buildfarm as a result of background auto-analyze
updating stats and changing the selected plan. Forestall that by
forcibly analyzing in foreground, instead. The new plan choice is
just as good for our purposes, since we really only care that an
index-only plan does not get selected.
Back-patch to 9.5, like the previous patch.
Discussion: https://postgr.es/m/14643.1539629304@sss.pgh.pa.us
Since 9.5, it's possible that some but not all columns of an index
support returning the indexed value for index-only scans. If the
same indexed column appears in index columns that behave both ways,
check_index_only() supposed that it'd be OK to do an index-only scan
testing that column; but that fails if we have to recheck the indexed
condition on one of the columns that doesn't support this.
In principle we could make this work by remapping the recheck expressions
to pull the value from a column that does support returning the indexed
value. But such cases are so weird and rare that, at least for now,
it doesn't seem worth the trouble. Instead, just teach check_index_only
that a value is returnable only if all the index columns containing it
are returnable, rather than any of them.
Per report from David Pereiro Lagares. Back-patch to 9.5 where the
possibility of this situation appeared.
Kyotaro Horiguchi
Discussion: https://postgr.es/m/1516210494.1798.16.camel@nlpgo.com
