问题描述
我正在使用Postgresql 13。
PostgreSQL通过以下查询使用索引：
SELECT *
FROM
"players"
WHERE team_id = 3
AND (
code ILIKE 'lushij'
OR
REPLACE(lastname||firstname,' ','') ILIKE '%lushij%'
OR REPLACE(firstname||lastname,'') ILIKE '%lushij%'
OR personal_info->>'houses' ILIKE '%lushij%'
)
LIMIT 15
Limit (cost=333.01..385.77 rows=15 width=360)
-> Bitmap Heap Scan on players (cost=333.01..4061.29 rows=1060 width=360)
Recheck Cond: ((code ~~* 'lushij'::text) OR (replace((lastname || firstname),' '::text,''::text) ~~* '%lushij%'::text) OR (replace((firstname || lastname),''::text) ~~* '%lushij%'::text) OR ((personal_info ->> 'houses'::text) ~~* '%lushij%'::text))
Filter: (team_id = 3)
-> BitmapOr (cost=333.01..333.01 rows=1060 width=0)
-> Bitmap Index Scan on players_code_trgm (cost=0.00..116.75 rows=100 width=0)
Index Cond: (code ~~* 'lushij'::text)
-> Bitmap Index Scan on players_replace_last_first_name_trgm (cost=0.00..66.40 rows=320 width=0)
Index Cond: (replace((lastname || firstname),''::text) ~~* '%lushij%'::text)
-> Bitmap Index Scan on players_replace_first_last_name_trgm (cost=0.00..66.40 rows=320 width=0)
Index Cond: (replace((firstname || lastname),''::text) ~~* '%lushij%'::text)
-> Bitmap Index Scan on players_personal_info_houses_trgm_idx (cost=0.00..82.40 rows=320 width=0)
Index Cond: ((personal_info ->> 'houses'::text) ~~* '%lushij%'::text)
对于相同的查询，但搜索文字少一个字符（从lushij到lushi）不使用索引：
SELECT *
FROM
"players"
WHERE team_id = 3
AND (
code ILIKE 'lushi'
OR
REPLACE(lastname||firstname,'') ILIKE '%lushi%'
OR REPLACE(firstname||lastname,'') ILIKE '%lushi%'
OR personal_info->>'houses' ILIKE '%lushi%'
)
LIMIT 15
Limit (cost=0.00..235.65 rows=15 width=360)
-> Seq Scan on players (cost=0.00..76853.53 rows=4892 width=360)
Filter: ((team_id = 3) AND ((code ~~* 'lushi'::text) OR (replace((lastname || firstname),''::text) ~~* '%lushi%'::text) OR (replace((firstname || lastname),''::text) ~~* '%lushi%'::text) OR ((personal_info ->> 'houses'::text) ~~* '%lushi%'::text)))
为什么？
更新：
如果我评论LIMIT 15行，则使用索引。
这里的结构：
玩家表结构-- ----------------------------
-- Table structure for players
-- ----------------------------
DROP TABLE IF EXISTS "public"."players";
CREATE TABLE "public"."players" (
"id" int8 NOT NULL DEFAULT nextval('players_id_seq'::regclass),"created_at" timestamptz(6) NOT NULL DEFAULT now(),"updated_at" timestamptz(6),"team_id" int8 NOT NULL,"firstname" text COLLATE "pg_catalog"."default","lastname" text COLLATE "pg_catalog"."default","code" text COLLATE "pg_catalog"."default","personal_info" jsonb
)
;
-- ----------------------------
-- Indexes structure for table players
-- ----------------------------
CREATE INDEX "players_personal_info_houses_trgm_idx" ON "public"."players" USING gin (
(personal_info ->> 'houses'::text) COLLATE "pg_catalog"."default" "public"."gin_trgm_ops"
);
CREATE INDEX "players_code_trgm" ON "public"."players" USING gin (
"code" COLLATE "pg_catalog"."default" "public"."gin_trgm_ops"
);
CREATE INDEX "players_lower_code" ON "public"."players" USING btree (
lower(code) COLLATE "pg_catalog"."default" "pg_catalog"."text_ops" ASC NULLS LAST
);
CREATE INDEX "players_replace_first_last_name_trgm" ON "public"."players" USING gin (
replace(firstname || lastname,''::text) COLLATE "pg_catalog"."default" "public"."gin_trgm_ops"
);
CREATE INDEX "players_replace_last_first_name_trgm" ON "public"."players" USING gin (
replace(lastname || firstname,''::text) COLLATE "pg_catalog"."default" "public"."gin_trgm_ops"
);
-- ----------------------------
-- Primary Key structure for table players
-- ----------------------------
ALTER TABLE "public"."players" ADD CONSTRAINT "players_pkey" PRIMARY KEY ("id");
-- ----------------------------
-- Foreign Keys structure for table players
-- ----------------------------
ALTER TABLE "public"."players" ADD CONSTRAINT "players_team_id_fkey" FOREIGN KEY ("team_id") REFERENCES "public"."teams" ("id") ON DELETE NO ACTION ON UPDATE NO ACTION;
解决方法
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