应用错误收集

我的笔记本电脑上安装了PostgreSQL 9.2和MySQL 5.5（InnoDB）。两个数据库引擎都使用默认安装并从同一CSV文件填充。我有'sales_reports'表与ca. 700K行。

情景1：

以下查询：

按名称从sales_reports组中选择名称，年份，地区，分支，年，地区，分支;
PostgreSQL 9.2：总查询运行时间：42.14秒，检索到18064行

PostgreSQL解释：

Group  (cost=165091.16..174275.61 rows=73476 width=58) (actual time=35196.959..41896.739 rows=18064 loops=1)
->  Sort  (cost=165091.16..166928.05 rows=734756 width=58) (actual time=35196.956..41704.549 rows=734756 loops=1)
    Sort Key: name, year, region, branch
    Sort Method: external merge  Disk: 49920kB
    ->  Seq Scan on sales_reports  (cost=0.00..38249.56 rows=734756 width=58) (actual time=0.048..282.331 rows=734756 loops=1)
Total runtime: 41906.628 ms

MySQL 5.5：总查询运行时间：4.4秒，检索到18064行

MySQL解释：

+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+
| id | select_type | table         | type | possible_keys | key  | key_len | ref  | rows   | Extra                           |
+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+
|  1 | SIMPLE      | sales_reports | ALL  | NULL          | NULL | NULL    | NULL | 729433 | Using temporary; Using filesort |
+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+

PostgreSQL慢10倍

情景2：

以下查询：

select name, year, region, branch, sum(sale) as sale from sales_reports group by name, year, region, branch;

PostgreSQL 9.2：总查询运行时间：42.51秒，检索到18064行

PostgreSQL解释：

GroupAggregate  (cost=165091.16..176847.26 rows=73476 width=64) (actual time=35160.911..42254.060 rows=18064 loops=1)
->  Sort  (cost=165091.16..166928.05 rows=734756 width=64) (actual time=35160.489..41857.986 rows=734756 loops=1)
    Sort Key: name, year, region, branch
    Sort Method: external merge  Disk: 54760kB
    ->  Seq Scan on sales_reports  (cost=0.00..38249.56 rows=734756 width=64) (actual time=0.047..296.347 rows=734756 loops=1)
Total runtime: 42264.790 ms

MySQL 5.5：总查询运行时间：8.15秒，检索到18064行

MySQL解释：

+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+
| id | select_type | table         | type | possible_keys | key  | key_len | ref  | rows   | Extra                           |
+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+
|  1 | SIMPLE      | sales_reports | ALL  | NULL          | NULL | NULL    | NULL | 729433 | Using temporary; Using filesort |
+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+

PostgreSQL慢5倍

情景3：

以下查询：

select name, year, region, sum(sale) as sale from sales_reports group by name, year, region;

PostgreSQL 9.2：总查询运行时间：1秒，检索到18064行

PostgreSQL解释：

HashAggregate  (cost=45597.12..45655.62 rows=5850 width=37) (actual time=758.396..759.756 rows=4644 loops=1)
->  Seq Scan on sales_reports  (cost=0.00..38249.56 rows=734756 width=37) (actual time=0.061..116.541 rows=734756 loops=1)
Total runtime: 760.133 ms

MySQL 5.5：总查询运行时间：5.8秒，检索到18064行

MySQL解释：

+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+
| id | select_type | table         | type | possible_keys | key  | key_len | ref  | rows   | Extra                           |
+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+
|  1 | SIMPLE      | sales_reports | ALL  | NULL          | NULL | NULL    | NULL | 729433 | Using temporary; Using filesort |
+----+-------------+---------------+------+---------------+------+---------+------+--------+---------------------------------+

PostgreSQL快5倍

任何想法为什么前两个场景在PostgreSQL上如此慢？

BTW，我在PostgreSQL的查询中为我正在使用的字段创建了索引，我没有在MySQL上创建任何索引。

谢谢，

马立克

PostgreSQL 9.2比MySQL 5.5慢10倍？

2 个答案: