maria-developers team mailing list archive

[kentoku <kentokushiba@xxxxxxxxx>]

Hi Sergei,

> > MDEV-16249 CHECKSUM TABLE for a spider table is not parallel and saves all data in memory in the spider head by default
>
> please remember to add an empty line after the first line in the commit
> comment, see https://git-scm.com/docs/git-commit#_discussion

O.K.

> > add checksum_null for setting null value of checksum
> >
> > diff --git a/sql/ha_partition.cc b/sql/ha_partition.cc
> > index 4e7fccca3af..e47da94ab20 100644
> > --- a/sql/ha_partition.cc
> > +++ b/sql/ha_partition.cc
> > @@ -8213,7 +8214,11 @@ int ha_partition::info(uint flag)
> >        stats.delete_length+= file->stats.delete_length;
> >        if (file->stats.check_time > stats.check_time)
> >          stats.check_time= file->stats.check_time;
> > -      stats.checksum+= file->stats.checksum;
> > +      if (!file->stats.checksum_null)
> > +      {
> > +        stats.checksum+= file->stats.checksum;
> > +        stats.checksum_null= FALSE;
> > +      }
>
> I'm not sure about it. When a checksum can be NULL?
>
> I mean, normally, if you do A+B+C and one of the values is NULL, then
> the whole sum is NULL. But here you simply skip NULLs, like in aggregate
> SUM() function.
>
> To understand what semantics works better in this case, I need to
> understand when a checksum can be NULL in spider.

Spider gets checksum from remote servers and Spider just uses this
value. Some cases a checksum table command returns NULL
from remote servers to Spider. Spider should use this result as is.
This is the reason that a checksum can be NULL in Spider.

> >      }
> >      if (stats.records && stats.records < 2 &&
> >          !(m_file[0]->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT))
>
> All other server changes look good, thanks.

O.K. Thanks.

Best Regards,
Kentoku


2019年6月6日(木) 4:22 Sergei Golubchik <serg@xxxxxxxxxxx>:
>
> Hi, Kentoku!
>
> On Jun 05, Kentoku wrote:
> > revision-id: a2520676ba1 (mariadb-10.4.5-10-ga2520676ba1)
> > parent(s): 31fe70290c5
> > author: Kentoku <kentokushiba@xxxxxxxxx>
> > committer: Kentoku <kentokushiba@xxxxxxxxx>
> > timestamp: 2019-05-23 14:36:18 +0900
> > message:
> >
> > MDEV-16249 CHECKSUM TABLE for a spider table is not parallel and saves all data in memory in the spider head by default
>
> please remember to add an empty line after the first line in the commit
> comment, see https://git-scm.com/docs/git-commit#_discussion
>
> > add checksum_null for setting null value of checksum
> >
> > diff --git a/sql/ha_partition.cc b/sql/ha_partition.cc
> > index 4e7fccca3af..e47da94ab20 100644
> > --- a/sql/ha_partition.cc
> > +++ b/sql/ha_partition.cc
> > @@ -8213,7 +8214,11 @@ int ha_partition::info(uint flag)
> >        stats.delete_length+= file->stats.delete_length;
> >        if (file->stats.check_time > stats.check_time)
> >          stats.check_time= file->stats.check_time;
> > -      stats.checksum+= file->stats.checksum;
> > +      if (!file->stats.checksum_null)
> > +      {
> > +        stats.checksum+= file->stats.checksum;
> > +        stats.checksum_null= FALSE;
> > +      }
>
> I'm not sure about it. When a checksum can be NULL?
>
> I mean, normally, if you do A+B+C and one of the values is NULL, then
> the whole sum is NULL. But here you simply skip NULLs, like in aggregate
> SUM() function.
>
> To understand what semantics works better in this case, I need to
> understand when a checksum can be NULL in spider.
>
> >      }
> >      if (stats.records && stats.records < 2 &&
> >          !(m_file[0]->ha_table_flags() & HA_STATS_RECORDS_IS_EXACT))
>
> All other server changes look good, thanks.
>
> Regards,
> Sergei
> Chief Architect MariaDB
> and security@xxxxxxxxxxx