pgsql: Fix bugs in information_schema.referential_constraints view.

Fix bugs in information_schema.referential_constraints view.

This view was being insufficiently careful about matching the FK constraint
to the depended-on primary or unique key constraint. That could result in
failure to show an FK constraint at all, or showing it multiple times, or
claiming that it depended on a different constraint than the one it really
does. Fix by joining via pg_depend to ensure that we find only the correct
dependency.

Back-patch, but don't bump catversion because we can't force initdb in back
branches. The next minor-version release notes should explain that if you
need to fix this in an existing installation, you can drop the
information_schema schema then re-create it by sourcing
$SHAREDIR/information_schema.sql in each database (as a superuser of
course).

Branch
------
REL8_2_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/9a743ffdd6b2fe7a24089fc97d8efc98884e337d

Modified Files
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src/backend/catalog/information_schema.sql | 26 +++++++++++++++-----------
1 files changed, 15 insertions(+), 11 deletions(-)