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Message #04908
Re: [Maria-discuss] Json Explain
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/
> >
> >
> >
>
>
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