From: Tom Lane <tgl@sss.pgh.pa.us>
To: g l <orangegrove@live.com>
cc: "pgsql-general@postgresql.org" <pgsql-general@postgresql.org>
Subject: =?UTF-8?Q?Re:_=E5=9B=9E=E5=A4=8D:_are_the_2_if-statements_in_join?=
         =?UTF-8?Q?=5Fis=5Flegal()_removable=3F?=
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Comments: In-reply-to g l <orangegrove@live.com>
	message dated "Sun, 11 May 2025 08:26:38 -0000"
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Date: Sun, 11 May 2025 11:31:39 -0400
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g l <orangegrove@live.com> writes:
> Then I run the core regression tests with "make installcheck-parallel
> " for v18beta1 as the document dictates. When the regression test is don=
e, only the last 2 log entries are found in logfile, the first 2 entries a=
re not printed at all. I run core regression also with v14.15 and v17.2, t=
he results are the same. What test suite do I need to run to cover the fir=
st 2 branches, or could you please show me a example query that can cover =
them? Thank you very much.

The coverage.postgresql.org results are, I believe, for check-world
not just the core tests.  You might try contrib/postgres_fdw first,
as that tends to be the non-core test with the most planner coverage.

In any case, the fact that a few of these lines are not reached by
test cases doesn't constitute a bug, and it most certainly doesn't
mean it'd be safe to remove them.  Most of the logic in join_is_legal
comes in symmetrical pairs of cases for the two possible orderings
of the two input relations.  It's just coincidental which of a pair
of cases will be exercised by a given phrasing of a SQL query.
So I don't feel that we're particularly short on coverage here:
one or the other code path is fully exercised in each case,
according to the coverage.postgresql.org results.

			regards, tom lane