这篇文章主要讲解了“怎么理解PostgreSQL创建数据表时的参数fillfactor”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“怎么理解PostgreSQL创建数据表时的参数fillfactor”吧！
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下面创建不同fillfactor的数据表,执行update操作
[local]:5432 pg12@testdb=# create table t_fillfactor_100(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=100);
CREATE TABLE
Time: 2.462 ms
[local]:5432 pg12@testdb=# create table t_fillfactor_70(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=70);
CREATE TABLE
Time: 3.437 ms
[local]:5432 pg12@testdb=# create table t_fillfactor_50(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=50);
CREATE TABLE
Time: 28.553 ms
[local]:5432 pg12@testdb=# insert into t_fillfactor_100(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
INSERT 0 1000000
Time: 3583.216 ms (00:03.583)
[local]:5432 pg12@testdb=# insert into t_fillfactor_70(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
INSERT 0 1000000
Time: 6506.113 ms (00:06.506)
[local]:5432 pg12@testdb=# insert into t_fillfactor_50(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
INSERT 0 1000000
Time: 3113.901 ms (00:03.114)
[local]:5432 pg12@testdb=# update t_fillfactor_100 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3');
UPDATE 1000000
Time: 10641.794 ms (00:10.642)
[local]:5432 pg12@testdb=# update t_fillfactor_70 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3');
UPDATE 1000000
Time: 8563.046 ms (00:08.563)
[local]:5432 pg12@testdb=# update t_fillfactor_50 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3');
UPDATE 1000000
Time: 4036.735 ms (00:04.037)可以看到,在插入时,fillfactor较高的数据表耗时较短,而在update时(全量),fillfactor的则有较大的优势.但,经过多次update后,耗时并不明显,原因在于经过多次update,每个块的空闲空间跟fillfactor=100的设定已相差无几.
[local]:5432 pg12@testdb=# update t_fillfactor_100 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3');
UPDATE 1000000
Time: 4276.404 ms (00:04.276)
[local]:5432 pg12@testdb=# update t_fillfactor_70 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3');
UPDATE 1000000
Time: 3856.575 ms (00:03.857)
[local]:5432 pg12@testdb=# update t_fillfactor_50 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3');
UPDATE 1000000
Time: 4364.962 ms (00:04.365)
[local]:5432 pg12@testdb=#重新创建表,使用pgbench进行测试
[local]:5432 pg12@testdb=# drop table if exists t_fillfactor_100;
t,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=70);
create table t_fillfactor_50(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=50);
insert into t_fillfactor_100(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
insert into t_fillfactor_70(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
insert into t_fillfactor_50(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
DROP TABLE
Time: 191.706 ms
[local]:5432 pg12@testdb=# drop table if exists t_fillfactor_70;
DROP TABLE
Time: 35.313 ms
[local]:5432 pg12@testdb=# drop table if exists t_fillfactor_50;
DROP TABLE
Time: 30.078 ms
[local]:5432 pg12@testdb=#
[local]:5432 pg12@testdb=# create table t_fillfactor_100(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=100);
CREATE TABLE
Time: 40.443 ms
[local]:5432 pg12@testdb=# create table t_fillfactor_70(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=70);
CREATE TABLE
Time: 1.334 ms
[local]:5432 pg12@testdb=# create table t_fillfactor_50(id int,c1 varchar(30),c2 varchar(30),c3 varchar(30)) with (fillfactor=50);
CREATE TABLE
Time: 1.024 ms
[local]:5432 pg12@testdb=#
[local]:5432 pg12@testdb=# insert into t_fillfactor_100(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
INSERT 0 1000000
Time: 2623.943 ms (00:02.624)
[local]:5432 pg12@testdb=# insert into t_fillfactor_70(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
INSERT 0 1000000
Time: 2543.045 ms (00:02.543)
[local]:5432 pg12@testdb=# insert into t_fillfactor_50(id,c1,c2,c3) select x,'c1'||x,'c2'||x,'c3'||x from generate_series(1,1000000) as x;
INSERT 0 1000000
Time: 2662.223 ms (00:02.662)
[local]:5432 pg12@testdb=#
使用pgbench进行测试
[pg12@localhost script]$ cat update_100.sql
\set id random(1,1000000)
begin;
update t_fillfactor_100 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3') where id= :id;
end;
[pg12@localhost script]$ cat update_70.sql
\set id random(1,1000000)
begin;
update t_fillfactor_70 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3') where id= :id;
end;
[pg12@localhost script]$ cat update_50.sql
\set id random(1,1000000)
begin;
update t_fillfactor_50 set c1=lpad('c1',30,'c1'),c2=lpad('c2',30,'c2'),c3=lpad('c3',30,'c3') where id= :id;
end;
[pg12@localhost script]$ pgbench -c 2 -C -f ~/script/update_100.sql -j 1 -n -T 60 -U pg12 testdb
transaction type: /home/pg12/script/update_100.sql
scaling factor: 1
query mode: simple
number of clients: 2
number of threads: 1
duration: 60 s
number of transactions actually processed: 691
latency average = 174.136 ms
tps = 11.485277 (including connections establishing)
tps = 11.625959 (excluding connections establishing)
[pg12@localhost script]$ pgbench -c 2 -C -f ~/script/update_70.sql -j 1 -n -T 60 -U pg12 testdb
transaction type: /home/pg12/script/update_70.sql
scaling factor: 1
query mode: simple
number of clients: 2
number of threads: 1
duration: 60 s
number of transactions actually processed: 652
latency average = 184.293 ms
tps = 10.852275 (including connections establishing)
tps = 10.981136 (excluding connections establishing)
[pg12@localhost script]$ pgbench -c 2 -C -f ~/script/update_50.sql -j 1 -n -T 60 -U pg12 testdb
transaction type: /home/pg12/script/update_50.sql
scaling factor: 1
query mode: simple
number of clients: 2
number of threads: 1
duration: 60 s
number of transactions actually processed: 627
latency average = 191.700 ms
tps = 10.432967 (including connections establishing)
tps = 10.551899 (excluding connections establishing)
[pg12@localhost script]$使用pgbench使用随机值进行测试,时长为60s,结果差别不大.
数据表大小的比较：
[local]:5432 pg12@testdb=# select pg_size_pretty(pg_relation_size('t_fillfactor_100'));
pg_size_pretty
----------------
58 MB
(1 row)
Time: 2.034 ms
[local]:5432 pg12@testdb=# select pg_size_pretty(pg_relation_size('t_fillfactor_70'));
pg_size_pretty
----------------
82 MB
(1 row)
Time: 1.469 ms
[local]:5432 pg12@testdb=# select pg_size_pretty(pg_relation_size('t_fillfactor_50'));
pg_size_pretty
----------------
117 MB
(1 row)
Time: 2.531 ms
[local]:5432 pg12@testdb=#分别是58MB vs 82MB vs 117MB ≈ 100 vs 70 vs 50
感谢各位的阅读，以上就是“怎么理解PostgreSQL创建数据表时的参数fillfactor”的内容了，经过本文的学习后，相信大家对怎么理解PostgreSQL创建数据表时的参数fillfactor这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是创新互联，小编将为大家推送更多相关知识点的文章，欢迎关注！
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