postgres 100w 1000w 10000w数据查询进行对比

<a href="https://www.cnblogs.com/mchina/archive/2013/04/19/3028573.html">查看index占用内存</a>
查看每个表的数据总数：
select count (*) from apples;

select count (*) from bananas;

select count (*) from cherries;

查看数据first_name or last_name 是jim的数据，并记录时间：

select * from apples where first_name = 'jim' or last_name = 'jim';

select * from bananas where first_name = 'jim' or last_name = 'jim';

select * from cherries where first_name = 'jim' or last_name = 'jim';

使用explain再次查询，记录时间：

explain select * from apples where first_name = 'jim' or last_name = 'jim';

explain select * from bananas where first_name = 'jim' or last_name = 'jim';

explain select * from cherries where first_name = 'jim' or last_name = 'jim';

为这3个表，的2个列，增加索引，记录：
1. 同样的SQL的查询时间, 包括 使用explain得到的结果也要记录。

select * from apples where first_name = 'jim' or last_name = 'jim';

select * from bananas where first_name = 'jim' or last_name = 'jim';

select * from cherries where first_name = 'jim' or last_name = 'jim';

explain select * from cherries where first_name = 'jim' or last_name = 'jim';

看一下index占用的空间(通过pg_admin应该可以看到，），可选任务。

select pg_size_pretty(pg_relation_size('apple_names'));

select pg_size_pretty(pg_relation_size('banana_names'));

 

select pg_size_pretty(pg_relation_size('cherry_names'));