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如何通过许多重复的 UNION 子查询来减少查询大小?

我使用 Postgres 13 并使用以下 DDL 定义了一个表:

CREATE TABLE item_codes (
    code    bytea                    NOT NULL,
    item_id bytea                    NOT NULL,
    time    TIMESTAMP WITH TIME ZONE NOT NULL,
    PRIMARY KEY (item_id, code)
);

CREATE INDEX ON item_codes (code, time, item_id);
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我使用以下查询:

SELECT DISTINCT time, item_id
FROM (
      (SELECT time, item_id
       FROM item_codes
       WHERE code = '\x3965623166306238383033393437613338373162313934383034366139653239'
       ORDER BY time, item_id
       LIMIT 100)
       UNION ALL
      (SELECT time, item_id
       FROM item_codes
       WHERE code = '\x3836653432356638366638636338393364373935343938303233343363373561'
       ORDER BY time, item_id
       LIMIT 100)
     ) AS items
ORDER …
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postgresql execution-plan union query-performance postgresql-performance

6
推荐指数
1
解决办法
608
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