maria-developers team mailing list archive

[김경남 <knamkim@xxxxxxxxx>]

Hi, Sergei !!

Thankyou for your response.

> I doubt it. The only reasonable way to get this is to query
performance
> schema. Either using SQL or with a lower-level handler interface. You
> can do either from your plugin.

Does a  lower-level handler interface means PSI? 

Is there a guide or document using PSI? It's a bit difficult to use PSI.

Regards,

kyungnam.

 

----------------------------Original Message----------------------------
From: Sergei Golubchik(serg@xxxxxxxxxxx)
To: 김경남/부책임연구원/신기술개발팀
Cc: community list[maria-developers@xxxxxxxxxxxxxxxxxxx]
Date: 2015.03.24 15:22 
Subject: Re: [Maria-developers] I wonder what elements add to
CMakeLists.txt 



Hi,  kyungnam!

On Mar 24,  kyungnam wrote:
> Hi, Sergei!
>
> Thanks for your advice and I agree with you.
>
> Accoring to your advice, It's not a good plan to pass some data to my
> plugin agent from sql_parse.cc because it needs to compile mariadb
> server.
>
> So I hava a another concept.
>
> Instead of put some code to sql_parse.cc, plugin collects a some data
> like below sample conceptual code.
>
> I_List_iterator<THD> it(threads);
> while ((tmp_thd=it++))
>         {
>                 if ((tmp_thd->get_command() == COM_QUERY)
> ||(tmp_thd->get_command() == COM_STMT_EXECUTE) )
>                   continue;
>                 char* sql = tmp_thd->query();
>                 if(sql)
>                 {
>                         ...
>                         send_data();      
>                 }
>         }
>
> In this case, I though that it doesn't need to  compile maria server,
> but it need to recompile whenever structure of THD is changed.

Yes, that's better. There are many plugins that access THD,
even though THD is not officially a part of the plugin API.

> Otherwise, if i hardcode directly into the server, can I contribute
> this community ?

Sure. You can contribute anything. The question is whether community
will accept and use your contribution. I think the your contribution
will be used more if it won't require anyone to recompile the server.

> Additionally, you asked me about what information I want to collect.
>
>  I want to collect data like below.
>
>  * events_statements_current
>  * events_stages_current
>  * events_waits_current
>  * events_statements_summary_by_digest

Oh, my. These are stored in the internal perfschema data structures. I
don't think you can get them even from sql_parse.cc

> These data easily collected by sql . but it's hard to collect by
access
> memory.(THD or something else.)
>
> I wonder if it is possible to collect these data without using pfs (or
> psi) data structure.

I doubt it. The only reasonable way to get this is to query performance
schema. Either using SQL or with a lower-level handler interface. You
can do either from your plugin.

Regards,
Sergei



 


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