select * from logs where uid=3 order by added limit 50;

 Limit  (cost=0.43..1749.70 rows=50 width=127) (actual time=3902.616..4044.502 rows=50 loops=1)
   ->  Index Scan using logs_added_idx on logs  (cost=0.43..58705.95 rows=1678 width=127) (actual time=3902.610..4044.432 rows=50 loops=1)
         Filter: (uid = 3)
         Rows Removed by Filter: 652848
 Planning time: 0.554 ms
 Execution time: 4044.665 ms
(6 rows)

+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+---------------------------------------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref   | rows | filtered | Extra                                 |
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+---------------------------------------+
|  1 | SIMPLE      | logs  | NULL       | ref  | uid           | uid  | 2       | const |  837 |   100.00 | Using index condition; Using filesort |
+----+-------------+-------+------------+------+---------------+------+---------+-------+------+----------+---------------------------------------+
1 row in set, 1 warning (0,03 sec)

explain analyze select * from logs order by added limit 50;
                                                               QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=0.43..3.06 rows=50 width=127) (actual time=0.582..0.669 rows=50 loops=1)
   ->  Index Scan using logs_added_idx on logs  (cost=0.43..56047.21 rows=1064383 width=127) (actual time=0.579..0.617 rows=50 loops=1)
 Planning time: 0.396 ms
 Execution time: 0.763 ms
(4 rows)

 Limit  (cost=0.43..144.68 rows=50 width=127) (actual time=0.330..0.668 rows=50 loops=1)
   ->  Index Scan using logs_uid_added_idx on logs  (cost=0.43..4841.47 rows=1678 width=127) (actual time=0.083..0.349 rows=50 loops=1)
         Index Cond: (uid = 3)
 Planning time: 2.207 ms
 Execution time: 0.832 ms
(5 строк)

 Limit  (cost=0.43..813.68 rows=50 width=127) (actual time=39.608..40.071 rows=50 loops=1)
   ->  Index Scan using logs_added_uid_idx on logs  (cost=0.43..27293.34 rows=1678 width=127) (actual time=39.587..40.001 rows=50 loops=1)
         Index Cond: (uid = 3)
 Planning time: 1.603 ms
 Execution time: 40.221 ms
(5 строк)

 Limit  (cost=0.43..144.68 rows=50 width=127) (actual time=0.084..0.238 rows=50 loops=1)
   ->  Index Scan using logs_uid_added_idx on logs  (cost=0.43..4841.47 rows=1678 width=127) (actual time=0.078..0.184 rows=50 loops=1)
         Index Cond: (uid = 3)
 Planning time: 0.239 ms
 Execution time: 0.301 ms
(5 строк)

select * from logs where uid=3 limit 50;

with d3 as (
select * from logs where uid=3 -- order by added limit 50;
) SELECT * from d3 order by added limit 50 

SHOW GLOBAL STATUS LIKE 'Qcache%';
+-------------------------+---------+
| Variable_name           | Value   |
+-------------------------+---------+
| Qcache_free_blocks      | 1       |
| Qcache_free_memory      | 1031832 |
| Qcache_hits             | 0       |
| Qcache_inserts          | 0       |
| Qcache_lowmem_prunes    | 0       |
| Qcache_not_cached       | 652155  |
| Qcache_queries_in_cache | 0       |
| Qcache_total_blocks     | 1       |
+-------------------------+---------+

EXPLAIN ANALYZE SELECT (_row).* FROM (
SELECT (
   SELECT test FROM test WHERE test.author=t.author ORDER BY rating DESC LIMIT 1
) AS _row
FROM (VALUES (29),(68),(45),(47),(50),(41),(11),(4),(83),(60)) AS t(author)
OFFSET 0) as _t;

EXPLAIN ANALYZE SELECT * FROM test WHERE author = ANY (ARRAY[29,68,45,47,50,41,11,4,83,60]) ORDER BY rating DESC LIMIT 1;

WITH sub AS (SELECT array[cn,code,num] AS p FROM phones WHERE type=2 AND id=57439)
SELECT id FROM phones WHERE type=1 AND array[cn,code,num] = ANY(SELECT p FROM sub);

SELECT id FROM phones WHERE type=1 AND ((cn,code,num) = (7,966,3126798) OR (cn,code,num) = (7,499,1204168) OR (cn,code,num) = (7,999,9858801)) GROUP BY id;

SELECT id FROM phones WHERE type=1 AND ((cn,code,num) = ((7,966,3126798) OR (7,499,1204168) OR (7,999,9858801)));

ОШИБКА:  аргумент конструкции OR должен иметь тип boolean, а не record
СТРОКА 1: ...id FROM phones WHERE type=1 AND ((cn,code,num) = ((7,966,312...
                                                               ^

SELECT(
select id from phones t1 where (t1.cn,t1.code,t1.num) = t2.ph
) AS _row
FROM (VALUES (7,966,3126798),(7,499,1204168),(7,999,9858801)) AS t2(ph) OFFSET 0;

ОШИБКА:  оператор не существует: record = integer
СТРОКА 2: ...elect id from phones t1 where (t1.cn,t1.code,t1.num) = t2.ph
                                                                  ^

SELECT * FROM (
SELECT * FROM t_t 

ORDER BY fld
LIMIT 30 +(SELECT count(1) FROM public.t_t  
	WHERE
		fld = (SELECT fld from (SELECT fld FROM public.t_t ORDER BY 1 LIMIT 30) last ORDER BY fld desc LIMIT 1)
		OR ( fld IS NULL AND (SELECT fld from (SELECT fld FROM public.t_t ORDER BY 1 LIMIT 30) last ORDER BY fld desc LIMIT 1)
			IS NULL
		)
	)
) buff
ORDER BY fld,t_id limit 30