用于性能的 PostgreSQL CROSS JOIN 索引

Question

这是我的第二部分。所以我有以下 table,

CREATE TABLE public.main_transaction
(
  id integer NOT NULL DEFAULT nextval('main_transaction_id_seq'::regclass),
  profile_id integer NOT NULL,
  request_no character varying(18),
  user_id bigint,
  .....
  CONSTRAINT main_transaction_pkey PRIMARY KEY (id),

  CONSTRAINT fk_main_transaction_user_id FOREIGN KEY (user_id)
      REFERENCES public.jhi_user (id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION,
      REFERENCES public.main_profile (id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION DEFERRABLE INITIALLY DEFERRED,

  CONSTRAINT main_transaction_profile_id_20_fk_main_profile_id FOREIGN KEY (profile_id)
      REFERENCES public.main_profile (id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION DEFERRABLE INITIALLY DEFERRED,
)

在 table 中，我的 table 中有外键，我正在使用 CROSS JOIN 到 link table 由 id 并导致性能下降（超过 100 万行数据在 12 秒 内返回结果）。更准确地说，我在 main_transaction（上面） table 中有一个 profile_id 列用于 profile table 和 个人资料 table 我有 customer_id 客户 table。所以，我的查询如下，

SELECT * FROM main_transaction t 
CROSS JOIN main_profile p 
CROSS JOIN main_customer c 
WHERE t.profile_id = p.id
AND p.user_id = c.id 
AND ( upper(t.request_no) LIKE upper(concat('%','0-90-6 12 ','%')) 
      OR upper(c.phone) LIKE upper(concat('%','0-90-6 12','%')) 
)

如果你需要profile和customertable的结构，我可以评论。

解释：

"Merge Join  (cost=27220.51..266464.85 rows=218 width=1692) (actual time=9399.370..9399.370 rows=0 loops=1)"
"  Merge Cond: (t.profile_id = p.id)"
"  Join Filter: ((upper((t.request_no)::text) ~~ upper(concat('%', ' 0-90-6 12 ', '%'))) OR (upper((c.phone)::text) ~~ upper(concat('%', ' 0-90-6 12, '%'))))"
"  Rows Removed by Join Filter: 1089489"
"  Buffers: shared hit=453158 read=413372, temp read=1560 written=1560"
"  ->  Index Scan using main_transaction_profile_id_idx on main_transaction t  (cost=0.43..198177.36 rows=1089489 width=1455) (actual time=0.004..3913.501 rows=1089489 loops=1)"
"        Buffers: shared hit=393656 read=410718"
"  ->  Materialize  (cost=27218.84..27645.70 rows=85372 width=237) (actual time=165.565..239.572 rows=1133650 loops=1)"
"        Buffers: shared hit=59502 read=2654, temp read=1560 written=1560"
"        ->  Sort  (cost=27218.84..27432.27 rows=85372 width=237) (actual time=165.560..188.746 rows=85368 loops=1)"
"              Sort Key: p.id"
"              Sort Method: external sort  Disk: 12480kB"
"              Buffers: shared hit=59502 read=2654, temp read=1560 written=1560"
"              ->  Merge Join  (cost=0.73..10594.24 rows=85372 width=237) (actual time=0.007..96.133 rows=85372 loops=1)"
"                    Merge Cond: (p.user_id = c.id)"
"                    Buffers: shared hit=59502 read=2654"
"                    ->  Index Scan using main_profile_e8701ad4 on main_profile p  (cost=0.29..3350.82 rows=85372 width=40) (actual time=0.003..24.892 rows=85372 loops=1)"
"                          Buffers: shared hit=29016 read=963"
"                    ->  Index Scan using main_customer_pkey on main_customer c  (cost=0.29..5963.16 rows=85506 width=197) (actual time=0.003..34.235 rows=85506 loops=1)"
"                          Buffers: shared hit=30486 read=1691"
"Planning time: 0.850 ms"
"Execution time: 9407.244 ms"

Answer 1

您的主要问题是 OR — 只要您的 WHERE 子句中有这样的 OR，您就永远无法获得良好的性能。

重写查询如下：

SELECT * FROM main_transaction t 
   JOIN main_profile p ON t.profile_id = p.id
   JOIN main_customer c ON p.user_id = c.id 
WHERE upper(t.request_no) LIKE upper(concat('%','0-90-6 12 ','%'))
UNION
SELECT * FROM main_transaction t 
   JOIN main_profile p ON t.profile_id = p.id
   JOIN main_customer c ON p.user_id = c.id 
WHERE upper(c.phone) LIKE upper(concat('%','0-90-6 12','%'));

然后确保您具有以下索引（除了 id 上的索引）：

CREATE INDEX ON main_transaction (profile_id);
CREATE INDEX ON main_transaction USING gin (upper(request_no) gin_trgm_ops);
CREATE INDEX ON main_profile (user_id);
CREATE INDEX ON main_customer USING gin (upper(phone) gin_trgm_ops);

这应该会有所作为。

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