[HACKERS] Keep ECPG comment for log_min_duration_statement

Hi,

I'd like to make it easier to analyze slow queries in ECPG using 
log_min_duration_statement. Especially when DBA and C application developer 
is different, DBA can feedback slow embedded query to the developer without 
difficulty and mistakes.

When our customers log and look into slower queries in C programs with 
embedded SQL, they use log_min_duration_statement.Using this logging option, 
SQL statement slower than a threshold will be displayed, but comments won't. 
That's because the pre-compiler (ECPG) removes all the comments when the 
pre-compiler converts C with embedded SQL to normal C code.

Without comments, DBA has difficulty with identifying to which C code 
the slow query belongs. And the exact slow query issue cannot be reported 
to the developer.   
So, I'd like to modify ecpg command not to remove some specific comments.

[Use-cases]
Here is a scenario:
1) Writing comments to embedded C file a) Describe the detailed usage of SQL in each comment.  b) Allocating id to each
SQL.   - application developer need to create corresponding table between id       and the detailed description of SQL

2) DBA takes advantage of comments especially when: a) Similar comments are displayed here and there.     In such a
case,each comment plays a role as an identifier and makes it     easier for DBA to identify SQL he/she looking for. b)
DBAand C application developer are different.    DBA can tell an application developer which query is slow without
mistakes.
 
[Interface]
add a new option "--enable-parse-comment" to ecpg command.<usage> ecpg --enable-parse-comment ,..., prog.pgc
This option enables ecpg command to pass on block comments (/* 〜 */) to converted C file.
The conditions to enable processing "block comments" as follows:- a block comment can be used with SELECT, INSERT,
UPDATE,or DELETE- a block comment can be placed right after keywords: SELECT, INSERT, UPDATE, DELETE or With- other
thanthose above error will occur- line comment(--) are ignored, which is same as log output when logging libpq
application
 
[Example]
1)[Correct comment position] this comment position is right after SELECTEXEC SQL SELECT /* qid=3, at line 30 in
yourApp.ecpg*/ * INTO :C1, :C2 FROM T1 WHERE C1=1;
 
2)[Incorrect comment position] this comment position is bad（error will occur)EXEC SQL /* qid=3, at line 30 in
yourApp.ecpg*/ SELECT * INTO :C1, :C2 FROM T1 WHERE C1=1;
 

As far as I searched, there seems no discussion on this topic.
Please let me know if exists.

Regards,
Okano Naoki
Fujitsu