[Feature Request]: explain prepared statement

[fengttt]

Is there an existing issue for the same feature request?

• I have checked the existing issues.

Is your feature request related to a problem?

prepare st from 'select * from t where i = ?';
set @a = 42;
execute st using @a; // runs fine

mysql> explain execute  st using @a;
ERROR 1064 (HY000): SQL parser error: You have an error in your SQL syntax; check the manual that corresponds to your MatrixOne server version for the right syntax to use. syntax error at line 1 column 25 near " using @a";
mysql>

Describe the feature you'd like

explain execute st using @A;
should print explain plan

Describe implementation you've considered

No response

Documentation, Adoption, Use Case, Migration Strategy

No response

Additional information

No response

[daviszhen]

explain 能看 execute 的plan。之前没有。
explain碰到execute的plan时，会将plan替换为prepare生成的plan 并替换其中的参数，最后显示出来。

语法：

explain force execute ...;
explain verbose force execute ...;
explain analyze force execute ...;
explain analyze verbose force execute ...;

加force关键字，是因为要与mysql兼容。mysql是不支持对execute进行explain的。
在实现过程中，碰到explain execute 语法冲突的问题。

• 一种解决冲突的办法是将execute 改为保留关键字。

• 一种是在execute前面区分用的保留关键字force。

为了与mysql保持兼容，execute没有改为保留关键字。最终选择了方案2。

支持下面的形式：

prepare st1 from 'select * from test.t2 where a = ? and b = ?';

set @a = 1, @b=1;

execute st1 using @a,@b;

explain force execute st1 using @a,@b;

explain verbose force execute st1 using @a,@b;

explain analyze force execute st1 using @a,@b;

explain analyze verbose force execute st1 using @a,@b;


//.  === 


prepare st2 from 'select * from test.t2 where a = 1 and b = 1';

execute st2;

explain force execute st2;

explain verbose force execute st2;

explain analyze force execute st2;

explain analyze verbose force execute st2;

[Ariznawlll]

test done.