maria-developers team mailing list archive

[Oleksandr Byelkin <sanja@xxxxxxxxxxxxxxxx>]

Am 29.01.2018 um 01:02 schrieb Sergei Golubchik:
> Hi, Oleksandr!
>
> 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.
> 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.
> 3. Please append the following to the commit comment:
> "
>    Without it, mysql_update() didn't know that there will be EXPLAIN
>    result set and was sending OK at the end of the update, which
>    conflicted with the EOF sent later by EXPLAIN.

OK
> "
>
> > On Sun, Jan 28, 2018 at 2:45 PM, Sergei Golubchik <serg@xxxxxxxxxxx> wrote:
> >
> > > Hi, Oleksandr!
> > >
> > > On Dec 22, Oleksandr Byelkin wrote:
> > > > revision-id: 980a5c318803d6aa7355e019869597976dcf19bf (mariadb-10.0.33-37-g980a5c31880)
> > > > parent(s): 042f763268c0f209e7c12e0a6a72bb5d204dfe29
> > > > author: Oleksandr Byelkin
> > > > committer: Oleksandr Byelkin
> > > > timestamp: 2017-12-22 14:00:10 +0100
> > > > message:
> > > >
> > > > MDEV-14572: Assertion `! is_set()' failed in Diagnostics_area::set_eof_status upon EXPLAIN UPDATE in PS
> > > >
> > > > Restore EXPAIN flag in SELECT_LEX before execution multi-update by flag in LEX
> > > > (the same but in other way made before INSERT/DELETE/SELECT)
> > > Please explain what was the reason for the bug, why the status was set
> > > twice, and how your change fixes it.
> Regards,
> Sergei
> Chief Architect MariaDB
> and security@xxxxxxxxxxx
>
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