Improve jumble squashing through CoerceViaIO and RelabelType

There's no principled reason for query jumbling to only remove the first
layer of RelabelType and CoerceViaIO.  Change it to see through as many
layers as there are.

2 files changed, 29 insertions, 20 deletions

diff --git a/contrib/pg_stat_statements/expected/squashing.out b/contrib/pg_stat_statements/expected/squashing.out
index 7b935d464ec..e978564ad72 100644
--- a/contrib/pg_stat_statements/expected/squashing.out
+++ b/contrib/pg_stat_statements/expected/squashing.out
@@ -645,7 +645,7 @@ SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset() IS NOT NULL AS t                   |     1
 (2 rows)
 
--- Multiple CoerceViaIO wrapping a constant. Will not squash
+-- Multiple CoerceViaIO are squashed
 SELECT pg_stat_statements_reset() IS NOT NULL AS t;
  t 
 ---
@@ -661,10 +661,10 @@ SELECT WHERE 1 = ANY(ARRAY[1::text::int::text::int, 1::text::int::text::int]);
 (1 row)
 
 SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
-                                  query                                  | calls 
--------------------------------------------------------------------------+-------
- SELECT WHERE $1 IN ($2::text::int::text::int, $3::text::int::text::int) |     2
- SELECT pg_stat_statements_reset() IS NOT NULL AS t                      |     1
+                       query                        | calls 
+----------------------------------------------------+-------
+ SELECT WHERE $1 IN ($2 /*, ... */)                 |     2
+ SELECT pg_stat_statements_reset() IS NOT NULL AS t |     1
 (2 rows)
 
 --
@@ -676,7 +676,7 @@ SELECT pg_stat_statements_reset() IS NOT NULL AS t;
  t
 (1 row)
 
--- if there is only one level of RelabelType, the list will be squashable
+-- However many layers of RelabelType there are, the list will be squashable.
 SELECT * FROM test_squash WHERE id IN
 	(1::oid, 2::oid, 3::oid, 4::oid, 5::oid, 6::oid, 7::oid, 8::oid, 9::oid);
  id | data 
@@ -689,8 +689,6 @@ SELECT ARRAY[1::oid, 2::oid, 3::oid, 4::oid, 5::oid, 6::oid, 7::oid, 8::oid, 9::
  {1,2,3,4,5,6,7,8,9}
 (1 row)
 
--- if there is at least one element with multiple levels of RelabelType,
--- the list will not be squashable
 SELECT * FROM test_squash WHERE id IN (1::oid, 2::oid::int::oid);
  id | data 
 ----+------
@@ -701,15 +699,25 @@ SELECT * FROM test_squash WHERE id = ANY(ARRAY[1::oid, 2::oid::int::oid]);
 ----+------
 (0 rows)
 
+-- RelabelType together with CoerceViaIO is also squashable
+SELECT * FROM test_squash WHERE id = ANY(ARRAY[1::oid::text::int::oid, 2::oid::int::oid]);
+ id | data 
+----+------
+(0 rows)
+
+SELECT * FROM test_squash WHERE id = ANY(ARRAY[1::text::int::oid, 2::oid::int::oid]);
+ id | data 
+----+------
+(0 rows)
+
 SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
-                               query                                | calls 
---------------------------------------------------------------------+-------
- SELECT * FROM test_squash WHERE id IN                             +|     1
-         ($1 /*, ... */)                                            | 
- SELECT * FROM test_squash WHERE id IN ($1::oid, $2::oid::int::oid) |     2
- SELECT ARRAY[$1 /*, ... */]                                        |     1
- SELECT pg_stat_statements_reset() IS NOT NULL AS t                 |     1
-(4 rows)
+                       query                        | calls 
+----------------------------------------------------+-------
+ SELECT * FROM test_squash WHERE id IN             +|     5
+         ($1 /*, ... */)                            | 
+ SELECT ARRAY[$1 /*, ... */]                        |     1
+ SELECT pg_stat_statements_reset() IS NOT NULL AS t |     1
+(3 rows)
 
 --
 -- edge cases
diff --git a/contrib/pg_stat_statements/sql/squashing.sql b/contrib/pg_stat_statements/sql/squashing.sql
index bd3243ec9cd..946e149831c 100644
--- a/contrib/pg_stat_statements/sql/squashing.sql
+++ b/contrib/pg_stat_statements/sql/squashing.sql
@@ -234,7 +234,7 @@ SELECT * FROM test_squash_jsonb WHERE data = ANY(ARRAY
 	 (SELECT '"10"')::jsonb]);
 SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
 
--- Multiple CoerceViaIO wrapping a constant. Will not squash
+-- Multiple CoerceViaIO are squashed
 SELECT pg_stat_statements_reset() IS NOT NULL AS t;
 SELECT WHERE 1 IN (1::text::int::text::int, 1::text::int::text::int);
 SELECT WHERE 1 = ANY(ARRAY[1::text::int::text::int, 1::text::int::text::int]);
@@ -245,14 +245,15 @@ SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
 --
 
 SELECT pg_stat_statements_reset() IS NOT NULL AS t;
--- if there is only one level of RelabelType, the list will be squashable
+-- However many layers of RelabelType there are, the list will be squashable.
 SELECT * FROM test_squash WHERE id IN
 	(1::oid, 2::oid, 3::oid, 4::oid, 5::oid, 6::oid, 7::oid, 8::oid, 9::oid);
 SELECT ARRAY[1::oid, 2::oid, 3::oid, 4::oid, 5::oid, 6::oid, 7::oid, 8::oid, 9::oid];
--- if there is at least one element with multiple levels of RelabelType,
--- the list will not be squashable
 SELECT * FROM test_squash WHERE id IN (1::oid, 2::oid::int::oid);
 SELECT * FROM test_squash WHERE id = ANY(ARRAY[1::oid, 2::oid::int::oid]);
+-- RelabelType together with CoerceViaIO is also squashable
+SELECT * FROM test_squash WHERE id = ANY(ARRAY[1::oid::text::int::oid, 2::oid::int::oid]);
+SELECT * FROM test_squash WHERE id = ANY(ARRAY[1::text::int::oid, 2::oid::int::oid]);
 SELECT query, calls FROM pg_stat_statements ORDER BY query COLLATE "C";
 
 --