Enable CHECK constraints to be declared NOT VALID

This means that they can initially be added to a large existing table
without checking its initial contents, but new tuples must comply to
them; a separate pass invoked by ALTER TABLE / VALIDATE can verify
existing data and ensure it complies with the constraint, at which point
it is marked validated and becomes a normal part of the table ecosystem.

An non-validated CHECK constraint is ignored in the planner for
constraint_exclusion purposes; when validated, cached plans are
recomputed so that partitioning starts working right away.

This patch also enables domains to have unvalidated CHECK constraints
attached to them as well by way of ALTER DOMAIN / ADD CONSTRAINT / NOT
VALID, which can later be validated with ALTER DOMAIN / VALIDATE
CONSTRAINT.

Thanks to Thom Brown, Dean Rasheed and Jaime Casanova for the various
reviews, and Robert Hass for documentation wording improvement
suggestions.

This patch was sponsored by Enova Financial.

4 files changed, 168 insertions, 0 deletions

diff --git a/src/test/regress/expected/alter_table.out b/src/test/regress/expected/alter_table.out
index 9ab84f983ed..b78b1510efb 100644
--- a/src/test/regress/expected/alter_table.out
+++ b/src/test/regress/expected/alter_table.out
@@ -196,14 +196,115 @@ DELETE FROM tmp3 where a=5;
 -- Try (and succeed) and repeat to show it works on already valid constraint
 ALTER TABLE tmp3 validate constraint tmpconstr;
 ALTER TABLE tmp3 validate constraint tmpconstr;
+-- Try a non-verified CHECK constraint
+ALTER TABLE tmp3 ADD CONSTRAINT b_greater_than_ten CHECK (b > 10); -- fail
+ERROR:  check constraint "b_greater_than_ten" is violated by some row
+ALTER TABLE tmp3 ADD CONSTRAINT b_greater_than_ten CHECK (b > 10) NOT VALID; -- succeeds
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_greater_than_ten; -- fails
+ERROR:  check constraint "b_greater_than_ten" is violated by some row
+DELETE FROM tmp3 WHERE NOT b > 10;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_greater_than_ten; -- succeeds
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_greater_than_ten; -- succeeds
+-- Test inherited NOT VALID CHECK constraints
+select * from tmp3;
+ a | b  
+---+----
+ 1 | 20
+(1 row)
+
+CREATE TABLE tmp6 () INHERITS (tmp3);
+CREATE TABLE tmp7 () INHERITS (tmp3);
+INSERT INTO tmp6 VALUES (6, 30), (7, 16);
+ALTER TABLE tmp3 ADD CONSTRAINT b_le_20 CHECK (b <= 20) NOT VALID;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_le_20;	-- fails
+ERROR:  check constraint "b_le_20" is violated by some row
+DELETE FROM tmp6 WHERE b > 20;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_le_20;	-- succeeds
+-- An already validated constraint must not be revalidated
+CREATE FUNCTION boo(int) RETURNS int IMMUTABLE STRICT LANGUAGE plpgsql AS $$ BEGIN RAISE NOTICE 'boo: %', $1; RETURN $1; END; $$;
+INSERT INTO tmp7 VALUES (8, 18);
+ALTER TABLE tmp7 ADD CONSTRAINT identity CHECK (b = boo(b));
+NOTICE:  boo: 18
+ALTER TABLE tmp3 ADD CONSTRAINT IDENTITY check (b = boo(b)) NOT VALID;
+NOTICE:  merging constraint "identity" with inherited definition
+ALTER TABLE tmp3 VALIDATE CONSTRAINT identity;
+NOTICE:  boo: 16
+NOTICE:  boo: 20
 -- Try (and fail) to create constraint from tmp5(a) to tmp4(a) - unique constraint on
 -- tmp4 is a,b
 ALTER TABLE tmp5 add constraint tmpconstr foreign key(a) references tmp4(a) match full;
 ERROR:  there is no unique constraint matching given keys for referenced table "tmp4"
+DROP TABLE tmp7;
+DROP TABLE tmp6;
 DROP TABLE tmp5;
 DROP TABLE tmp4;
 DROP TABLE tmp3;
 DROP TABLE tmp2;
+-- NOT VALID with plan invalidation -- ensure we don't use a constraint for
+-- exclusion until validated
+set constraint_exclusion TO 'partition';
+create table nv_parent (d date); 
+create table nv_child_2010 () inherits (nv_parent);
+create table nv_child_2011 () inherits (nv_parent);
+alter table nv_child_2010 add check (d between '2010-01-01'::date and '2010-12-31'::date) not valid;
+alter table nv_child_2011 add check (d between '2011-01-01'::date and '2011-12-31'::date) not valid;
+explain (costs off) select * from nv_parent where d between '2011-08-01' and '2011-08-31';
+                                   QUERY PLAN                                    
+---------------------------------------------------------------------------------
+ Result
+   ->  Append
+         ->  Seq Scan on nv_parent
+               Filter: ((d >= '08-01-2011'::date) AND (d <= '08-31-2011'::date))
+         ->  Seq Scan on nv_child_2010 nv_parent
+               Filter: ((d >= '08-01-2011'::date) AND (d <= '08-31-2011'::date))
+         ->  Seq Scan on nv_child_2011 nv_parent
+               Filter: ((d >= '08-01-2011'::date) AND (d <= '08-31-2011'::date))
+(8 rows)
+
+create table nv_child_2009 (check (d between '2009-01-01'::date and '2009-12-31'::date)) inherits (nv_parent);
+explain (costs off) select * from nv_parent where d between '2011-08-01'::date and '2011-08-31'::date;
+                                   QUERY PLAN                                    
+---------------------------------------------------------------------------------
+ Result
+   ->  Append
+         ->  Seq Scan on nv_parent
+               Filter: ((d >= '08-01-2011'::date) AND (d <= '08-31-2011'::date))
+         ->  Seq Scan on nv_child_2010 nv_parent
+               Filter: ((d >= '08-01-2011'::date) AND (d <= '08-31-2011'::date))
+         ->  Seq Scan on nv_child_2011 nv_parent
+               Filter: ((d >= '08-01-2011'::date) AND (d <= '08-31-2011'::date))
+(8 rows)
+
+explain (costs off) select * from nv_parent where d between '2009-08-01'::date and '2009-08-31'::date;
+                                   QUERY PLAN                                    
+---------------------------------------------------------------------------------
+ Result
+   ->  Append
+         ->  Seq Scan on nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+         ->  Seq Scan on nv_child_2010 nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+         ->  Seq Scan on nv_child_2011 nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+         ->  Seq Scan on nv_child_2009 nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+(10 rows)
+
+-- after validation, the constraint should be used
+alter table nv_child_2011 VALIDATE CONSTRAINT nv_child_2011_d_check;
+explain (costs off) select * from nv_parent where d between '2009-08-01'::date and '2009-08-31'::date;
+                                   QUERY PLAN                                    
+---------------------------------------------------------------------------------
+ Result
+   ->  Append
+         ->  Seq Scan on nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+         ->  Seq Scan on nv_child_2010 nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+         ->  Seq Scan on nv_child_2009 nv_parent
+               Filter: ((d >= '08-01-2009'::date) AND (d <= '08-31-2009'::date))
+(8 rows)
+
 -- Foreign key adding test with mixed types
 -- Note: these tables are TEMP to avoid name conflicts when this test
 -- is run in parallel with foreign_key.sql.
diff --git a/src/test/regress/expected/domain.out b/src/test/regress/expected/domain.out
index 34bc31ab380..521fe01fa17 100644
--- a/src/test/regress/expected/domain.out
+++ b/src/test/regress/expected/domain.out
@@ -352,6 +352,17 @@ alter domain con drop constraint t;
 insert into domcontest values (-5); --fails
 ERROR:  value for domain con violates check constraint "con_check"
 insert into domcontest values (42);
+-- Test ALTER DOMAIN .. CONSTRAINT .. NOT VALID
+create domain things AS INT;
+CREATE TABLE thethings (stuff things);
+INSERT INTO thethings (stuff) VALUES (55);
+ALTER DOMAIN things ADD CONSTRAINT meow CHECK (VALUE < 11);
+ERROR:  column "stuff" of table "thethings" contains values that violate the new constraint
+ALTER DOMAIN things ADD CONSTRAINT meow CHECK (VALUE < 11) NOT VALID;
+ALTER DOMAIN things VALIDATE CONSTRAINT meow;
+ERROR:  column "stuff" of table "thethings" contains values that violate the new constraint
+UPDATE thethings SET stuff = 10;
+ALTER DOMAIN things VALIDATE CONSTRAINT meow;
 -- Confirm ALTER DOMAIN with RULES.
 create table domtab (col1 integer);
 create domain dom as integer;
diff --git a/src/test/regress/sql/alter_table.sql b/src/test/regress/sql/alter_table.sql
index b5d76ea68e3..bb2c27718a0 100644
--- a/src/test/regress/sql/alter_table.sql
+++ b/src/test/regress/sql/alter_table.sql
@@ -236,12 +236,41 @@ DELETE FROM tmp3 where a=5;
 ALTER TABLE tmp3 validate constraint tmpconstr;
 ALTER TABLE tmp3 validate constraint tmpconstr;
 
+-- Try a non-verified CHECK constraint
+ALTER TABLE tmp3 ADD CONSTRAINT b_greater_than_ten CHECK (b > 10); -- fail
+ALTER TABLE tmp3 ADD CONSTRAINT b_greater_than_ten CHECK (b > 10) NOT VALID; -- succeeds
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_greater_than_ten; -- fails
+DELETE FROM tmp3 WHERE NOT b > 10;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_greater_than_ten; -- succeeds
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_greater_than_ten; -- succeeds
+
+-- Test inherited NOT VALID CHECK constraints
+select * from tmp3;
+CREATE TABLE tmp6 () INHERITS (tmp3);
+CREATE TABLE tmp7 () INHERITS (tmp3);
+
+INSERT INTO tmp6 VALUES (6, 30), (7, 16);
+ALTER TABLE tmp3 ADD CONSTRAINT b_le_20 CHECK (b <= 20) NOT VALID;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_le_20;	-- fails
+DELETE FROM tmp6 WHERE b > 20;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT b_le_20;	-- succeeds
+
+-- An already validated constraint must not be revalidated
+CREATE FUNCTION boo(int) RETURNS int IMMUTABLE STRICT LANGUAGE plpgsql AS $$ BEGIN RAISE NOTICE 'boo: %', $1; RETURN $1; END; $$;
+INSERT INTO tmp7 VALUES (8, 18);
+ALTER TABLE tmp7 ADD CONSTRAINT identity CHECK (b = boo(b));
+ALTER TABLE tmp3 ADD CONSTRAINT IDENTITY check (b = boo(b)) NOT VALID;
+ALTER TABLE tmp3 VALIDATE CONSTRAINT identity;
 
 -- Try (and fail) to create constraint from tmp5(a) to tmp4(a) - unique constraint on
 -- tmp4 is a,b
 
 ALTER TABLE tmp5 add constraint tmpconstr foreign key(a) references tmp4(a) match full;
 
+DROP TABLE tmp7;
+
+DROP TABLE tmp6;
+
 DROP TABLE tmp5;
 
 DROP TABLE tmp4;
@@ -250,6 +279,23 @@ DROP TABLE tmp3;
 
 DROP TABLE tmp2;
 
+-- NOT VALID with plan invalidation -- ensure we don't use a constraint for
+-- exclusion until validated
+set constraint_exclusion TO 'partition';
+create table nv_parent (d date); 
+create table nv_child_2010 () inherits (nv_parent);
+create table nv_child_2011 () inherits (nv_parent);
+alter table nv_child_2010 add check (d between '2010-01-01'::date and '2010-12-31'::date) not valid;
+alter table nv_child_2011 add check (d between '2011-01-01'::date and '2011-12-31'::date) not valid;
+explain (costs off) select * from nv_parent where d between '2011-08-01' and '2011-08-31';
+create table nv_child_2009 (check (d between '2009-01-01'::date and '2009-12-31'::date)) inherits (nv_parent);
+explain (costs off) select * from nv_parent where d between '2011-08-01'::date and '2011-08-31'::date;
+explain (costs off) select * from nv_parent where d between '2009-08-01'::date and '2009-08-31'::date;
+-- after validation, the constraint should be used
+alter table nv_child_2011 VALIDATE CONSTRAINT nv_child_2011_d_check;
+explain (costs off) select * from nv_parent where d between '2009-08-01'::date and '2009-08-31'::date;
+
+
 -- Foreign key adding test with mixed types
 
 -- Note: these tables are TEMP to avoid name conflicts when this test
diff --git a/src/test/regress/sql/domain.sql b/src/test/regress/sql/domain.sql
index 1cc447b8a24..449b4234a5c 100644
--- a/src/test/regress/sql/domain.sql
+++ b/src/test/regress/sql/domain.sql
@@ -259,6 +259,16 @@ alter domain con drop constraint t;
 insert into domcontest values (-5); --fails
 insert into domcontest values (42);
 
+-- Test ALTER DOMAIN .. CONSTRAINT .. NOT VALID
+create domain things AS INT;
+CREATE TABLE thethings (stuff things);
+INSERT INTO thethings (stuff) VALUES (55);
+ALTER DOMAIN things ADD CONSTRAINT meow CHECK (VALUE < 11);
+ALTER DOMAIN things ADD CONSTRAINT meow CHECK (VALUE < 11) NOT VALID;
+ALTER DOMAIN things VALIDATE CONSTRAINT meow;
+UPDATE thethings SET stuff = 10;
+ALTER DOMAIN things VALIDATE CONSTRAINT meow;
+
 -- Confirm ALTER DOMAIN with RULES.
 create table domtab (col1 integer);
 create domain dom as integer;