如果 2 个索引 ILIKE 条件之间存在 OR 条件，Postgres 不会使用我的索引

问题描述 投票：0回答：1

我们的客户和仓库表有以下索引：

CREATE UNIQUE INDEX "idx_49921_PK__PERSONA" ON public.persona USING btree ("ID");

CREATE INDEX persona_full_name ON public.persona USING gin (((("NOMBREPERSONA" || ' '::text) || "APELLIDOPERSONA")) gin_trgm_ops, "EMAILPERSONA" gin_trgm_ops);

CREATE UNIQUE INDEX "idx_49740_PK_BODEGA" ON public.warehouse USING btree (id);

CREATE INDEX warehouse_name ON public.warehouse USING gin (name gin_trgm_ops);

如果我执行以下查询：

explain analyze select *
from
    package as "Package"
inner join persona as "Persona" on
    "Package"."customer_id" = "Persona"."ID"
left outer join "warehouse" as "Warehouse" on
    "Package"."IDBODEGA" = "Warehouse"."id"
where
    "Warehouse"."name" ILIKE '%test name%' or
    "Persona"."EMAILPERSONA" ILIKE '%test name%' or
    "Persona"."NOMBREPERSONA" || ' ' || "Persona"."APELLIDOPERSONA" ILIKE '%test name%'

它返回这个：

Gather  (cost=19659.56..66121.41 rows=250 width=261) (actual time=1526.310..1680.903 rows=0 loops=1)
  Workers Planned: 2
  Workers Launched: 2
  ->  Hash Left Join  (cost=18659.56..65096.41 rows=104 width=261) (actual time=1502.623..1502.714 rows=0 loops=3)
        Hash Cond: ("Package"."IDBODEGA" = "Warehouse".id)
        Filter: (("Warehouse".name ~~* '%test name%'::text) OR ("Persona"."EMAILPERSONA" ~~* '%test name%'::text) OR ((("Persona"."NOMBREPERSONA" || ' '::text) || "Persona"."APELLIDOPERSONA") ~~* '%test name%'::text))
        Rows Removed by Filter: 282885
        ->  Parallel Hash Join  (cost=18530.66..64038.97 rows=353608 width=196) (actual time=309.438..540.409 rows=282885 loops=3)
              Hash Cond: ("Package".customer_id = "Persona"."ID")
              ->  Parallel Seq Scan on package "Package"  (cost=0.00..26217.08 rows=353608 width=154) (actual time=0.284..103.231 rows=282886 loops=3)
              ->  Parallel Hash  (cost=12532.18..12532.18 rows=281718 width=46) (actual time=91.819..91.819 rows=225375 loops=3)
                    Buckets: 65536  Batches: 16  Memory Usage: 3968kB
                    ->  Parallel Seq Scan on persona "Persona"  (cost=0.00..12532.18 rows=281718 width=46) (actual time=0.103..35.280 rows=225375 loops=3)
        ->  Hash  (cost=79.51..79.51 rows=3951 width=37) (actual time=1.216..1.216 rows=3951 loops=3)
              Buckets: 4096  Batches: 1  Memory Usage: 299kB
              ->  Seq Scan on warehouse "Warehouse"  (cost=0.00..79.51 rows=3951 width=37) (actual time=0.213..0.700 rows=3951 loops=3)
Planning Time: 0.998 ms
Execution Time: 1681.071 ms

所以它没有使用任何一个索引。

但是如果我单独执行此条件（同时保留查询的其余部分）：

where "Warehouse"."name" ILIKE '%test name%'

它返回这个：

Gather  (cost=1064.45..28219.84 rows=34 width=261) (actual time=37.400..40.770 rows=0 loops=1)
  Workers Planned: 2
  Workers Launched: 2
  ->  Nested Loop  (cost=64.45..27216.44 rows=14 width=261) (actual time=0.318..0.319 rows=0 loops=3)
        ->  Hash Join  (cost=64.03..27209.48 rows=14 width=191) (actual time=0.317..0.318 rows=0 loops=3)
              Hash Cond: ("Package"."IDBODEGA" = "Warehouse".id)
              ->  Parallel Seq Scan on package "Package"  (cost=0.00..26217.08 rows=353608 width=154) (actual time=0.196..0.196 rows=1 loops=3)
              ->  Hash  (cost=64.02..64.02 rows=1 width=37) (actual time=0.062..0.062 rows=0 loops=3)
                    Buckets: 1024  Batches: 1  Memory Usage: 8kB
                    ->  Bitmap Heap Scan on warehouse "Warehouse"  (cost=60.00..64.02 rows=1 width=37) (actual time=0.061..0.062 rows=0 loops=3)
                          Recheck Cond: (name ~~* '%test name%'::text)
                          ->  Bitmap Index Scan on warehouse_name  (cost=0.00..60.00 rows=1 width=0) (actual time=0.060..0.060 rows=0 loops=3)
                                Index Cond: (name ~~* '%test name%'::text)
        ->  Index Scan using "idx_49921_PK__PERSONA" on persona "Persona"  (cost=0.42..0.50 rows=1 width=37) (never executed)
              Index Cond: ("ID" = "Package".customer_id)
Planning Time: 0.589 ms
Execution Time: 40.821 ms

使用warehouse_name索引，查询时间少很多。

同样，如果我这样做：

where
    "Persona"."EMAILPERSONA" ILIKE '%test name%'
    OR "Persona"."NOMBREPERSONA" || ' ' || "Persona"."APELLIDOPERSONA" ILIKE '%test name%'

返回：

Gather  (cost=1666.98..28849.55 rows=167 width=261) (actual time=38.049..41.531 rows=0 loops=1)
  Workers Planned: 2
  Workers Launched: 2
  ->  Nested Loop Left Join  (cost=666.98..27832.85 rows=70 width=261) (actual time=1.846..1.848 rows=0 loops=3)
        ->  Hash Join  (cost=666.70..27812.01 rows=70 width=187) (actual time=1.845..1.847 rows=0 loops=3)
              Hash Cond: ("Package".customer_id = "Persona"."ID")
              ->  Parallel Seq Scan on package "Package"  (cost=0.00..26217.08 rows=353608 width=154) (actual time=0.171..0.171 rows=1 loops=3)
              ->  Hash  (cost=665.04..665.04 rows=133 width=37) (actual time=1.621..1.622 rows=0 loops=3)
                    Buckets: 1024  Batches: 1  Memory Usage: 8kB
                    ->  Bitmap Heap Scan on persona "Persona"  (cost=177.06..665.04 rows=133 width=37) (actual time=1.621..1.621 rows=0 loops=3)
                          Recheck Cond: (("EMAILPERSONA" ~~* '%test name%'::text) OR ((("NOMBREPERSONA" || ' '::text) || "APELLIDOPERSONA") ~~* '%test name%'::text))
                          ->  BitmapOr  (cost=177.06..177.06 rows=133 width=0) (actual time=1.619..1.620 rows=0 loops=3)
                                ->  Bitmap Index Scan on persona_full_name  (cost=0.00..88.49 rows=65 width=0) (actual time=0.981..0.981 rows=0 loops=3)
                                      Index Cond: ("EMAILPERSONA" ~~* '%test name%'::text)
                                ->  Bitmap Index Scan on persona_full_name  (cost=0.00..88.51 rows=68 width=0) (actual time=0.637..0.637 rows=0 loops=3)
                                      Index Cond: ((("NOMBREPERSONA" || ' '::text) || "APELLIDOPERSONA") ~~* '%test name%'::text)
        ->  Index Scan using "idx_49740_PK_BODEGA" on warehouse "Warehouse"  (cost=0.28..0.30 rows=1 width=37) (never executed)
              Index Cond: (id = "Package"."IDBODEGA")
Planning Time: 0.541 ms
Execution Time: 41.705 ms

所以它也使用索引。

问题是当我尝试同时使用两个索引时。

我在这里可以做些什么吗？原始查询要长得多，几乎需要 3 秒，我做了这个查询试图隔离这个问题。

postgresql indexing
1个回答
0
投票

没有用于执行位图或跨不同表组合位图的机制。

您可以将其分成两个查询，每个查询仅引用 ILIKE 条件中的一张表，然后使用 UNION 或 UNION ALL 将它们合并为一个查询。 您需要确保它以您认为可接受的方式处理重复项。

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