maria-discuss team mailing list archive

[Peter Laursen <peter_laursen@xxxxxxxxxx>]

I don't claim we will necessarily need it! :-)

I was only asking.  No more comments at the moment.  I will update here if
I think I have a reason to!

Thanks for considering!


-- Peter

On Sun, Sep 30, 2012 at 7:13 PM, Igor Babaev <igor@xxxxxxxxxxxx> wrote:

> Peter,
>
> You are right that EXPLAIN in any format has nothing to do with the
> optimizer. Looking at the piece of the MySQL code that forms the strings
> for the EXPLAIN anyone could easily come up with the patch providing
> JSON format for the EXPLAIN (even with the extensions of MySQL 5.6) and
> it would take him/her 2-3 days at most (maybe even a few hours).
>
> That's why we are reluctant to pull the existing implementation of JSON
> format from MySQL 5.6 into MariaDB. The patch is huge and overburdened
> with unneeded complexities. Besides it contains a lot of "restructuring"
> code that has nothing to do with the feature itself.
>
> Personally I think that the content in the current EXPLAIN (including
> the content of the EXPLAIN EXTENDED) is so shallow that any graphical
> representation hardly can help it (compare it, for example, with the
> info provided by MS SQL server).
>
> If, nevertheless, you badly need the feature and is ready to co-sponsor
> the feature (together with MP AB) we could discuss the details of the
> possible simple implementation. And of course we will support it in
> MariaDB if anybody else provide us with a patch for such an implementation.
>
> Regards,
> Igor.
>
> On 09/30/2012 04:23 AM, Peter Laursen wrote:
> > I do not see why this should be a concern for the optimizer team.
> >
> > The output from EXPLAIN (in any format) does not affect optimizer's
> > operation but only provides information of *optimizer result*. The
> > format chosen is (?) applied is *after* not *before* or *during* the
> > optimization process.
> >
> > TRADITIONAL EXPLAIN returns the result as an **array**.  JSON EXPLAIN
> > returns the result as a single (Json-formatted) **string** (not unlike
> > SHOW ENGINE INNODB STATUS, btw).  But both should have exactly the same
> > information - and if they don't it is a bug with JSON EXPLAIN in MySQL
> > 5.6 IMO.
> >
> > But as I am not well-versed in server internals, I could have
> > ovelooked/misunderstood something, of course.
> >
> > -- Peter
> >
> > On Fri, Sep 28, 2012 at 5:18 PM, Peter Laursen <peter_laursen@xxxxxxxxxx
> > <mailto:peter_laursen@xxxxxxxxxx>> wrote:
> >
> >     @wlad is completely right!
> >
> >     Workbench introduced a Visual Explain based on JSON EXPLAIN as
> >     Blogged here:
> >     http://www.arubin.org/blog/2012/09/26/mysql-visual-explain/
> >
> >     The very reason why JSON EXPLAIN was introduced in MySQL 5.6 could
> >     be that Oracle develops the server and tools (WB, Enterprirse
> >     Monitor primarily) in parallel.  Some recently introduced features
> >     in the server could be introduced for the primary reason that they
> >     should be 'exploited' by MEM and/or WB.  JSON EXPLAIN is one.
> >     Another example is the Performance_Schema table introduced in 5.6.6
> >     (I don't remember the table name)  that records an 'aggregated
> >     summary' of queries' performance. Actually this table has about the
> >     same information as what MONyog 'Query Analyzer' module displays in
> >     its most simple display mode (but MONyog can be 'drilled down' to a
> >     more detailed view).
> >
> >     So Oracle *thinks* the server and their most important tools *as a
> >     whole*, I think. We/Webyog cannot ignore this, as we compete with
> >     Oracle (SQLyog <-> WB, MONyog <-> MEM).  We have to consider to
> >     implement a more intuitive and advisory way of displaying EXPLAIN
> >     results (for non-expert users primarily of course). The JSON format
> >     is interesting for us in the context.
> >
> >     -- Peter
> >
> >
> >
> >
> >
> >     On Fri, Sep 28, 2012 at 4:50 PM, Vladislav Vaintroub
> >     <wlad@xxxxxxxxxxxxxxxx <mailto:wlad@xxxxxxxxxxxxxxxx>> wrote:
> >
> >
> >
> >         > -----Original Message-----
> >         > From: maria-discuss-
> >         > bounces+wlad=montyprogram.com@xxxxxxxxxxxxxxxxxxx
> >         <mailto:montyprogram.com@xxxxxxxxxxxxxxxxxxx> [mailto:maria-
> >         <mailto:maria->
> >         > discuss-bounces+wlad=montyprogram.com@xxxxxxxxxxxxxxxxxxx
> >         <mailto:montyprogram.com@xxxxxxxxxxxxxxxxxxx>] On Behalf
> >         > Of Michael Widenius
> >         > Sent: Freitag, 28. September 2012 16:04
> >         > To: Peter Laursen; igor@xxxxxxxxxxxx
> >         <mailto:igor@xxxxxxxxxxxx>; timour@xxxxxxxxxxxx
> >         <mailto:timour@xxxxxxxxxxxx>;
> >         > psergey@xxxxxxxxxxxx <mailto:psergey@xxxxxxxxxxxx>
> >         > Cc: Maria Discuss; Maria Developers
> >         > Subject: Re: [Maria-discuss] [Maria-developers] Json Explain
> >         >
> >         >
> >         > For the moment we don't have a plan for that.
> >         >
> >         > The main reason is that the MariadB optimizer people don't
> >         like the
> >         > implementation and we are not sure how useful the current
> output
> >         > really is.
> >         >
> >
> >         I guess json  is not for normal people to read , it is for
> >         programs to
> >         analyze and ,for example, display in a visually pleasing
> >         fashion. I believe
> >         this is the reason why Peter asks, and (I guess) the reason why
> >         Workbench
> >         has visual explain feature now for 5.6+.
> >         http://www.arubin.org/blog/2012/09/26/mysql-visual-explain/
> >
> >
> >
>
>