Postgres 14

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CREATE TABLE tbl (id int, customer_id text, item text, value text, timestamp timestamp);    
INSERT INTO tbl VALUES
    (1, '001', 'price', '1000', '2021-11-01 01:00:00'),
    (2, '001', 'price', '1500', '2021-11-02 01:00:00'),
    (3, '001', 'condition', 'good', '2021-11-03 01:00:00'),
    (4, '002', 'condition', 'bad', '2021-11-04 01:00:00'),
    (5, '002', 'condition', 'good', '2021-11-05 01:00:00'),
    (6, '002', 'price', '1000', '2021-11-06 01:00:00'),
    (7, '001', 'condition', 'good', '2021-11-07 01:00:00'),
    (8, '001', 'price', '1400', '2021-11-08 01:00:00'),
    (9, '002', 'price', '1500', '2021-11-09 01:00:00'),
    (10, '001', 'condition', 'ok', '2021-11-10 01:00:00'),
    (11, '002', 'price', '1600', '2021-11-11 01:00:00'),
    (12, '002', 'price', '1550', '2021-11-12 01:00:00')
;

CREATE INDEX tbl_condition_special_idx ON tbl (customer_id, timestamp DESC, value) WHERE item = 'condition';
CREATE INDEX tbl_price_special_idx     ON tbl (customer_id, timestamp DESC, value) WHERE item = 'price';

12 rows affected

customer_id	price	condition
001	1400	ok
002	1550	good