作者
digoal
日期
2020-04-03
标签
PostgreSQL , hook , pg_parallizator , 后台 , 会话 , 并行创建多索引
背景
在创建索引的位置, 通过加HOOK, 将创建索引的sql通过新的连接发送到另一个会话执行, 例如你要创建10个索引, 那么可以开10个会话, 从而支持并行创建索引.
这个动作在hook内完成, 你执行create index的时候就好像瞬间完成, 实际上是在另一个会话执行, 所以你可以继续执行下一条create index. pg_parallizator.max_workers控制并行度, 达到并行度之后, 就不会开启新的会话, 直到有索引创建结束, 才可以加入新的create index.
This extension can reduce time of loading data in database by building indexes in parallel. It launches new backend for execution of "CREATE INDEX" statement. Maximal number of concurrently constructed indexes is limited by "pg_parallizator.max_workers" parameter (default value is 8). When this limit is reached, current backends waits completion of most recently started index creation. Also backend waits completion of all started workers before exit.
pg_parallizator establishes local connection to the database, so such access should be enabled.
pg_parallizator run in parallel only explicitly created indexes (not one created implicitly during table creation, such as primary key index). Also indexes created with CONCURRENTLY qualifier are not considered (because building them in parallel may cause deadlock).
To use pg_parallizator please load correspondent library using the following command:
LOAD 'pg_parallizator';
例子:
load 'pg_parallizator';
drop table if exists huge;
\timing
create table huge (pk integer primary key, k1 real, k2 real, k3 real, k4 real, k5 real, k6 real, k7 real, k8 real);
insert into huge values (generate_series(1,10000000), random(), random(), random(), random(), random(), random(), random(), random());
create index on huge(k1);
create index on huge(k2);
create index on huge(k3);
create index on huge(k4);
create index on huge(k5);
create index on huge(k6);
create index on huge(k7);
create index on huge(k8);
参考
https://github.com/postgrespro/pg_parallizator
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