maria-developers team mailing list archive

[Oleksandr Byelkin <sanja@xxxxxxxxxxxxxxxx>]

Hi, Sergei!

Am 18.06.2018 um 14:14 schrieb Sergei Golubchik:
> Hi, Oleksandr!
>
> On Jun 11, Oleksandr Byelkin wrote:
> > Am 29.01.2018 um 01:02 schrieb Sergei Golubchik:
> > > On Jan 28, Oleksandr Byelkin wrote:
> > > > Hi, Sergei!
> > > >
> > > > Flag in SELECT_LEX options dropped at the end of execution (in our case
> > > > prepare). All commands where EXPLAIN is possible restore the flag in main
> > > > SELECT_LEX (in mysql_explain_union())  except UPDATE (because it do
> > > > not use mysql_explain_union()
> > > > for explain). Without the flag it first try to send OK (as part of update)
> > > > then EOF as part of EXPLAIN.
> > > Ok.
> > >
> > > 1. Why does it not use mysql_explain_union() ?
> > It is question to them who made explain for non SELECT statements
> > (probably Sergey Petrunia) as I can see it just have a bit different
> > call pathes.
> So all UPDATE/DELETE restore the flag, and only multi-update didn't?
> What about multi-delete?
all except this.
> Better to add tests with PREPARE and all non-select explainable
> commands to test it and to make sure it won't break in the future.
OK
> > > 2. Why EXPLAIN flag is need to be removed and restored anyway?
> > Because it is how our EXPLAIN works (written without taking into account
> > re-execution). If remove the flag cleanup it will change output of
> > prepared explain EXPLAIN.
> Yes, I understand why the flag has to be restored.
> But why it has to be removed?
it was explanation why it should be removed something do not work 
otherwise. I tried and explain starts changing on second call.
> Regards,
> Sergei
> Chief Architect MariaDB
> and security@xxxxxxxxxxx