问如何让Postgres“放弃”过滤？

EN

WITH matching_countries AS (
    SELECT *,
           1 AS match_level
    FROM directory.country
    WHERE /* first condition */
  UNION ALL
    SELECT *,
           2 AS match_level
    FROM directory.country 
    WHERE /* second condition */
  UNION
    ...
)
SELECT *
FROM matching_countries
ORDER BY match_level, length(name)
LIMIT 1;

SELECT version();

CREATE TABLE country
        ( id integer not null primary key
        , name text
        , canonical_name text
        );
INSERT INTO country(id, name, canonical_name) VALUES
 ( 1, 'United Kingdom', 'UK' )
, ( 2, 'Deutchland', 'DE' )
, ( 3, 'France', 'FR' )
, ( 4, 'Nederland', 'NL' )
        ;

CREATE TABLE country_alias
        ( id SERIAL not null primary key
        , country_id integer not null REFERENCES country(id)
        , name text
        );
INSERT INTO country_alias(country_id, name) VALUES
 ( 1, 'Britain' )
, ( 1, 'Great Britain' )
, ( 2, 'Germany')
, ( 3, 'Marianne')
, ( 3, 'Ohlala')
, ( 4, 'Holland' )
, ( 4, 'Kaaskoppen' )
        ;

----------

prepare onion(integer, text, text) AS
WITH one AS (
  SELECT 'one' AS tag, * FROM country
  WHERE id = $1
  )
, two AS (
        SELECT 'two' AS tag, * FROM country
        WHERE NOT EXISTS ( SELECT * FROM one)
        AND ( name = $2
           OR name ILIKE $3
           OR canonical_name = $2
           OR canonical_name ILIKE $3
           )
        )
, three AS (
        SELECT 'three' AS tag, *
        FROM country co
        WHERE NOT EXISTS ( SELECT * FROM two)
        AND EXISTS ( SELECT *
        FROM country_alias ca
        WHERE ca.country_id = co.id
        AND ( ca.name = $2 OR ca.name ILIKE $3)
        )
)
SELECT * FROM (
        SELECT * FROM one
        UNION ALL SELECT * FROM two
        UNION ALL SELECT * FROM three
        ) six
-- ORDER BY LENGTH(name) ASC
LIMIT 1
        ;

-- EXPLAIN ANALYZE EXECUTE onion(1,'Huge Britain', 'Uk');
EXPLAIN ANALYZE EXECUTE onion(6,'Huge Britain', 'U%');

EXECUTE onion(9,'Ned', 'kaas%');
EXPLAIN ANALYZE EXECUTE onion(11,'Huge Britain', 'U%');

 PostgreSQL 11.6 on armv7l-unknown-linux-gnueabihf, compiled by gcc (Raspbian 8.3.0-6+rpi1) 8.3.0, 32-bit
(1 row)

CREATE TABLE
INSERT 0 4
CREATE TABLE
INSERT 0 7
PREPARE
                                                                           QUERY PLAN                                                                           
----------------------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=90.37..90.39 rows=1 width=100) (actual time=0.163..0.165 rows=1 loops=1)
   CTE one
     ->  Index Scan using country_pkey on country  (cost=0.15..2.37 rows=1 width=100) (actual time=0.054..0.055 rows=0 loops=1)
           Index Cond: (id = 6)
   CTE two
     ->  Result  (cost=0.02..27.02 rows=850 width=100) (actual time=0.083..0.084 rows=1 loops=1)
           One-Time Filter: (NOT $1)
           InitPlan 2 (returns $1)
             ->  CTE Scan on one one_1  (cost=0.00..0.02 rows=1 width=0) (actual time=0.002..0.003 rows=0 loops=1)
           ->  Seq Scan on country country_1  (cost=0.00..27.00 rows=850 width=68) (actual time=0.069..0.070 rows=1 loops=1)
                 Filter: ((name = 'Huge Britain'::text) OR (name ~~* 'U%'::text) OR (canonical_name = 'Huge Britain'::text) OR (canonical_name ~~* 'U%'::text))
   CTE three
     ->  Result  (cost=35.52..60.98 rows=425 width=100) (never executed)
           One-Time Filter: (NOT $3)
           InitPlan 4 (returns $3)
             ->  CTE Scan on two two_1  (cost=0.00..17.00 rows=850 width=0) (never executed)
           ->  Hash Join  (cost=35.50..60.96 rows=425 width=68) (never executed)
                 Hash Cond: (co.id = ca.country_id)
                 ->  Seq Scan on country co  (cost=0.00..18.50 rows=850 width=68) (never executed)
                 ->  Hash  (cost=33.00..33.00 rows=200 width=4) (never executed)
                       ->  HashAggregate  (cost=31.00..33.00 rows=200 width=4) (never executed)
                             Group Key: ca.country_id
                             ->  Seq Scan on country_alias ca  (cost=0.00..28.00 rows=1200 width=4) (never executed)
                                   Filter: ((name = 'Huge Britain'::text) OR (name ~~* 'U%'::text))
   ->  Append  (cost=0.00..31.90 rows=1276 width=100) (actual time=0.158..0.159 rows=1 loops=1)
         ->  CTE Scan on one  (cost=0.00..0.02 rows=1 width=100) (actual time=0.060..0.061 rows=0 loops=1)
         ->  CTE Scan on two  (cost=0.00..17.00 rows=850 width=100) (actual time=0.092..0.093 rows=1 loops=1)
         ->  CTE Scan on three  (cost=0.00..8.50 rows=425 width=100) (never executed)
 Planning Time: 2.560 ms
 Execution Time: 1.169 ms
(30 rows)

  tag  | id |   name    | canonical_name 
-------+----+-----------+----------------
 three |  4 | Nederland | NL
(1 row)

->  CTE Scan on one  (cost=0.00..0.02 rows=1 width=100)
(actual time=0.060..0.061 rows=0 loops=1)
->  CTE Scan on two  (cost=0.00..17.00 rows=850 width=100)
(actual time=0.092..0.093 rows=1 loops=1)
->  CTE Scan on three  (cost=0.00..8.50 rows=425 width=100)
(never executed)