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我有一个表:PostgreSQL的简单的选择是缓慢
CREATE TABLE my_table
(
id integer NOT NULL DEFAULT nextval('seq_my_table_id'::regclass),
fk_id1 integer NOT NULL,
fk_id2 smallint NOT NULL,
name character varying(255) NOT NULL,
description text,
currency_name character varying(3) NOT NULL,
created timestamp with time zone NOT NULL DEFAULT now(),
updated timestamp with time zone NOT NULL DEFAULT now(),
CONSTRAINT "PK_my_table_id" PRIMARY KEY (id),
CONSTRAINT "FK_my_table_fk_id1" FOREIGN KEY (fk_id1)
REFERENCES my_table2 (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION DEFERRABLE INITIALLY DEFERRED,
CONSTRAINT "FK_my_table_fk_id2" FOREIGN KEY (fk_id2)
REFERENCES my_table3 (id) MATCH SIMPLE
ON UPDATE NO ACTION ON DELETE NO ACTION DEFERRABLE INITIALLY DEFERRED
)
WITH (
OIDS=FALSE,
autovacuum_enabled=true,
autovacuum_vacuum_threshold=50,
autovacuum_vacuum_scale_factor=0.2,
autovacuum_analyze_threshold=50,
autovacuum_analyze_scale_factor=0.1,
autovacuum_vacuum_cost_delay=20,
autovacuum_vacuum_cost_limit=200,
autovacuum_freeze_min_age=50000000,
autovacuum_freeze_max_age=200000000,
autovacuum_freeze_table_age=150000000
);
ALTER TABLE my_table
OWNER TO postgres;
CREATE INDEX my_table_fk_id1
ON my_table
USING btree
(fk_id1);
CREATE INDEX my_table_fk_id2
ON my_table
USING btree
(fk_id2);
表中的记录计数
select count(id) from my_table; --24061
select count(id) from my_table2; --24061
select count(id) from my_table3; --123
执行时间
select * from my_table -- ~17sec
vacuum/analyze
- 不影响
description
- 长度〜4000字符在每行
postgres.conf
- 非标准设置
版本:9.1
选择除描述各个领域减少执行时间到〜1.5秒
如何icrease选择速度描述?
UPD
--explain analyze select * from my_table
"Seq Scan on my_table (cost=0.00..3425.79 rows=24079 width=1015) (actual time=0.019..17.238 rows=24079 loops=1)"
"Total runtime: 18.649 ms"
你正在使用哪个应用程序来显示'select *'语句的结果?报告哪个运行时报告了解释select * from my_table' –
'select *'只是例子,但是'select fk_id1,fk_id2,name,currency_name,description' - 使用(相同的17秒),也见问题更新 – cetver
运行时* *在服务器上**仅有18 **毫秒**(18.649ms)。这意味着如果您的前端需要17 *秒*,则通过网络(或在客户端应用程序内)发送行的时间会丢失 –