maria-developers team mailing list archive

[Sergei Petrunia <psergey@xxxxxxxxxxxx>]

Ok, thanks for the input. I'll change the formatting to prefix each line with
'explain:', and remove XML-like tags.

On Sat, Oct 19, 2013 at 08:32:51AM -0700, Jeremy Zawodny wrote:
> Agreed.  Make it easy to grep and don't pretend the log is an XML file. :-)
> 
> Jeremy
> 
> 
> On Sat, Oct 19, 2013 at 8:26 AM, Eric Bergen <eric.bergen@xxxxxxxxx> wrote:
> 
> > I don't understand why you need both the <explain> xml style tag and
> > the double # to denote an explain entry. I would prefer to see each
> > line prefixed with # explain: to make it similar to the other info
> > lines above and get rid of the <explain>.
> >
> > By prefixing each line with # explain: it makes grepping explain plans
> > easier than looking for a start and end tag on different lines.
> >
> > On Fri, Oct 18, 2013 at 4:59 PM, Sergei Golubchik <serg@xxxxxxxxxxx>
> > wrote:
> > > Hi, Sergei!
> > >
> > > On Oct 18, Sergei Petrunia wrote:
> > >> Hello,
> > >>
> > >> After recent changes in the [SHOW] EXPLAIN architecture in MariaDB, it
> > became
> > >> really easy to add an option to print EXPLAIN(*) output into the slow
> > query log,
> > >> so I went ahead and implemented it.
> > >>
> > >> @@log_slow_verbosity has got a 'explain' flag, and if it is on, the
> > slow query
> > >> log entries look like this:
> > >>
> > >> # Time: 131017 21:26:02
> > >> # User@Host: root[root] @ localhost []
> > >> # Thread_id: 2  Schema: dbt3sf1  QC_hit: No
> > >> # Query_time: 5.535819  Lock_time: 0.000350  Rows_sent: 1
> >  Rows_examined: 65633
> > >> ## <explain>
> > >> ##   id select_type     table   type    possible_keys   key     key_len
> > ref     rows    Extra
> > >> ##   1  SIMPLE  nation  ref     PRIMARY,n_name  n_name  26      const
> > 1       Using where; Using index
> > >> ##   1  SIMPLE  customer        ref     PRIMARY,i_c_nationkey
> > i_c_nationkey   5       dbt3sf1.nation.n_nationkey      25124   Using index
> > >> ##   1  SIMPLE  orders  ref     i_o_custkey     i_o_custkey     5
> > dbt3sf1.customer.c_custkey      7       Using index
> > >> ## </explain>
> > >> SET timestamp=1382030762;
> > >> select count(*) from customer, orders, nation where c_custkey=o_custkey
> > and c_nationkey=n_nationkey and n_name='GERMANY';
> > >>
> > >> It seems, pt-slow-query-log has no problem parsing this.
> > >>
> > >> Open questions:
> > >>
> > >> - Is this syntax OK?
> > >
> > > Yes, assuming you use tabs as column separators, not spaces.
> > >
> > >> - Currently, some statements (like SHOW KEYS) print a dumb explain that
> > >> shows that full table scan is used. There is a suggestion to not print
> > >> EXPLAIN for any SHOW statements. Is this ok?
> > >
> > > Yes. If users will complain we can always change it back later.
> > >
> > > Regards,
> > > Sergei
> > >
> > > _______________________________________________
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> >
> >
> >
> > --
> > Eric Bergen
> > eric.bergen@xxxxxxxxx
> > http://www.ebergen.net
> >
> > _______________________________________________
> > Mailing list: https://launchpad.net/~maria-developers
> > Post to     : maria-developers@xxxxxxxxxxxxxxxxxxx
> > Unsubscribe : https://launchpad.net/~maria-developers
> > More help   : https://help.launchpad.net/ListHelp
> >

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-- 
BR
 Sergei
-- 
Sergei Petrunia, Software Developer
MariaDB | Skype: sergefp | Blog: http://s.petrunia.net/blog