Add tests for foreign keys with case-insensitive collations

Some of the behaviors of the different referential actions, such as
the difference between NO ACTION and RESTRICT are best illustrated
using a case-insensitive collation.  So add some tests for that.

(What is actually being tested here is the behavior with values that
are "distinct" (binary different) but compare as equal.  Another way
to do that would be with positive and negative zeroes with float
types.  But this way seems nicer and more flexible.)

Discussion: https://www.postgresql.org/message-id/ea5b2777-266a-46fa-852f-6fca6ec480ad@eisentraut.org

Author: petere

src/test/regress/expected/collate.icu.utf8.out

@@ -2024,6 +2024,68 @@ CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
 CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);  -- error
 ERROR:  foreign key constraint "test11fk_x_fkey" cannot be implemented
 DETAIL:  Key columns "x" of the referencing table and "x" of the referenced table have incompatible collations: "case_sensitive" and "case_insensitive".  If either collation is nondeterministic, then both collations have to be the same.
+-- foreign key actions
+-- Some of the behaviors are most easily visible with a
+-- case-insensitive collation.
+CREATE TABLE test12pk (x text COLLATE case_insensitive PRIMARY KEY);
+CREATE TABLE test12fk (a int, b text COLLATE case_insensitive REFERENCES test12pk (x) ON UPDATE NO ACTION);
+INSERT INTO test12pk VALUES ('abc');
+INSERT INTO test12fk VALUES (1, 'abc'), (2, 'ABC');
+UPDATE test12pk SET x = 'ABC' WHERE x = 'abc';  -- ok
+SELECT * FROM test12pk;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT * FROM test12fk;  -- no updates here
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+DROP TABLE test12pk, test12fk;
+CREATE TABLE test12pk (x text COLLATE case_insensitive PRIMARY KEY);
+CREATE TABLE test12fk (a int, b text COLLATE case_insensitive REFERENCES test12pk (x) ON UPDATE RESTRICT);
+INSERT INTO test12pk VALUES ('abc');
+INSERT INTO test12fk VALUES (1, 'abc'), (2, 'ABC');
+UPDATE test12pk SET x = 'ABC' WHERE x = 'abc';  -- restrict violation
+ERROR:  update or delete on table "test12pk" violates foreign key constraint "test12fk_b_fkey" on table "test12fk"
+DETAIL:  Key (x)=(abc) is still referenced from table "test12fk".
+SELECT * FROM test12pk;
+  x  
+-----
+ abc
+(1 row)
+
+SELECT * FROM test12fk;
+ a |  b  
+---+-----
+ 1 | abc
+ 2 | ABC
+(2 rows)
+
+DROP TABLE test12pk, test12fk;
+CREATE TABLE test12pk (x text COLLATE case_insensitive PRIMARY KEY);
+CREATE TABLE test12fk (a int, b text COLLATE case_insensitive REFERENCES test12pk (x) ON UPDATE CASCADE);
+INSERT INTO test12pk VALUES ('abc');
+INSERT INTO test12fk VALUES (1, 'abc'), (2, 'ABC');
+UPDATE test12pk SET x = 'ABC' WHERE x = 'abc';  -- ok
+SELECT * FROM test12pk;
+  x  
+-----
+ ABC
+(1 row)
+
+SELECT * FROM test12fk;  -- was updated
+ a |  b  
+---+-----
+ 1 | ABC
+ 2 | ABC
+(2 rows)
+
+DROP TABLE test12pk, test12fk;
 -- partitioning
 CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
 CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');

src/test/regress/sql/collate.icu.utf8.sql

@@ -743,6 +743,36 @@ CREATE TABLE test10fk (x text COLLATE case_insensitive REFERENCES test10pk (x) O
 CREATE TABLE test11pk (x text COLLATE case_insensitive PRIMARY KEY);
 CREATE TABLE test11fk (x text COLLATE case_sensitive REFERENCES test11pk (x) ON UPDATE CASCADE ON DELETE CASCADE);  -- error
 
+-- foreign key actions
+-- Some of the behaviors are most easily visible with a
+-- case-insensitive collation.
+CREATE TABLE test12pk (x text COLLATE case_insensitive PRIMARY KEY);
+CREATE TABLE test12fk (a int, b text COLLATE case_insensitive REFERENCES test12pk (x) ON UPDATE NO ACTION);
+INSERT INTO test12pk VALUES ('abc');
+INSERT INTO test12fk VALUES (1, 'abc'), (2, 'ABC');
+UPDATE test12pk SET x = 'ABC' WHERE x = 'abc';  -- ok
+SELECT * FROM test12pk;
+SELECT * FROM test12fk;  -- no updates here
+DROP TABLE test12pk, test12fk;
+
+CREATE TABLE test12pk (x text COLLATE case_insensitive PRIMARY KEY);
+CREATE TABLE test12fk (a int, b text COLLATE case_insensitive REFERENCES test12pk (x) ON UPDATE RESTRICT);
+INSERT INTO test12pk VALUES ('abc');
+INSERT INTO test12fk VALUES (1, 'abc'), (2, 'ABC');
+UPDATE test12pk SET x = 'ABC' WHERE x = 'abc';  -- restrict violation
+SELECT * FROM test12pk;
+SELECT * FROM test12fk;
+DROP TABLE test12pk, test12fk;
+
+CREATE TABLE test12pk (x text COLLATE case_insensitive PRIMARY KEY);
+CREATE TABLE test12fk (a int, b text COLLATE case_insensitive REFERENCES test12pk (x) ON UPDATE CASCADE);
+INSERT INTO test12pk VALUES ('abc');
+INSERT INTO test12fk VALUES (1, 'abc'), (2, 'ABC');
+UPDATE test12pk SET x = 'ABC' WHERE x = 'abc';  -- ok
+SELECT * FROM test12pk;
+SELECT * FROM test12fk;  -- was updated
+DROP TABLE test12pk, test12fk;
+
 -- partitioning
 CREATE TABLE test20 (a int, b text COLLATE case_insensitive) PARTITION BY LIST (b);
 CREATE TABLE test20_1 PARTITION OF test20 FOR VALUES IN ('abc');