什麼是PostgreSQL的EXPLAIN ANALYZE的MySQL相當於

Question

我想在MySQL中得到一個詳細的查詢計劃，類似於PostgreSQL中的EXPLAIN ANALYSE展示。有沒有相同的東西？

Answer 1

編輯：雖然不是直接等同或詳細的講解分析這裏有一些工具，你可以看看

MySQL提供講解和過程分析（）
http://dev.mysql.com/doc/refman/5.0/en/explain.html
http://dev.mysql.com/doc/refman/5.0/en/procedure-analyse.html

Answer 2

我有在MySQL有EXPLAIN EXTENDED之前沒有使用過PostgreSQL，它給出的信息比EXPLAIN更多，可能會給你提供你正在尋找的信息。

Answer 3

只是爲了清楚起見，在接受的答案評論（沒有足夠的業力加評論）

過程分析（）是用於不同的目的解釋， 分析了指定列的數據集，並建議最好的數據類型， 即當我們有1000行varchar（255）並且想要檢查我們真正需要多少長度時它很有用，fe它可能會告訴VARCHAR（23）就足夠了

Answer 4

EXPLAIN EXTENDED

MariaDB的/ MySQL的提供一些所謂的EXPLAIN EXTENDED。然而，EXPLAIN ANALYZE沒有替代品。 EXPLAIN EXTENDED不提供任何時間信息，並且內部分解不詳細。

Name: 'EXPLAIN' 
Description: 
Syntax: 
EXPLAIN [explain_type] SELECT select_options 

explain_type: 
    EXTENDED 
    | PARTITIONS 

Or: 

EXPLAIN tbl_name 

The EXPLAIN statement can be used either as a way to obtain information 
about how MySQL executes a statement, or as a synonym for DESCRIBE: 

o When you precede a SELECT statement with the keyword EXPLAIN, MySQL 
    displays information from the optimizer about the query execution 
    plan. That is, MySQL explains how it would process the statement, 
    including information about how tables are joined and in which order. 
    EXPLAIN EXTENDED can be used to obtain additional information. 

    For information about using EXPLAIN and EXPLAIN EXTENDED to obtain 
    query execution plan information, see 
    https://mariadb.com/kb/en/explain/. 

o EXPLAIN PARTITIONS is useful only when examining queries involving 
    partitioned tables. For details, see 
    http://dev.mysql.com/doc/refman/5.5/en/partitioning-info.html. 

o EXPLAIN tbl_name is synonymous with DESCRIBE tbl_name or SHOW COLUMNS 
    FROM tbl_name. For information about DESCRIBE and SHOW COLUMNS, see 
    [HELP DESCRIBE], and [HELP SHOW COLUMNS]. 

URL: https://mariadb.com/kb/en/explain/ 

例如，這一點taken from this example，

EXPLAIN ANALYZE SELECT * 
FROM history AS h1 
WHERE EXISTS (
    SELECT 1 
    FROM history AS h2 
    WHERE h1.lead_id = h2.lead_id 
    GROUP BY lead_id 
    HAVING count(is_first OR NULL) > 1 
); 

會產生這樣的事情在PostgreSQL上，

             QUERY PLAN              
-------------------------------------------------------------------------------------------------------------------- 
Seq Scan on history h1 (cost=0.00..82680.50 rows=1100 width=9) (actual time=0.048..0.065 rows=3 loops=1) 
    Filter: (SubPlan 1) 
    Rows Removed by Filter: 3 
    SubPlan 1 
    -> GroupAggregate (cost=0.00..37.57 rows=1 width=5) (actual time=0.007..0.007 rows=0 loops=6) 
      Group Key: h2.lead_id 
      Filter: (count((h2.is_first OR NULL::boolean)) > 1) 
      Rows Removed by Filter: 0 
      -> Seq Scan on history h2 (cost=0.00..37.50 rows=11 width=5) (actual time=0.003..0.004 rows=2 loops=6) 
       Filter: (h1.lead_id = lead_id) 
       Rows Removed by Filter: 4 
Planning time: 0.149 ms 
Execution time: 0.123 ms 
(13 rows) 

雖然這是MySQL的等價的，

+------+--------------------+-------+------+---------------+------+---------+------+------+----------+-------------+ 
| id | select_type  | table | type | possible_keys | key | key_len | ref | rows | filtered | Extra  | 
+------+--------------------+-------+------+---------------+------+---------+------+------+----------+-------------+ 
| 1 | PRIMARY   | h1 | ALL | NULL   | NULL | NULL | NULL | 6 | 100.00 | Using where | 
| 2 | DEPENDENT SUBQUERY | h2 | ALL | NULL   | NULL | NULL | NULL | 6 | 100.00 | Using where | 
+------+--------------------+-------+------+---------------+------+---------+------+------+----------+-------------+ 
2 rows in set, 2 warnings (0.00 sec)