maria-developers team mailing list archive

[Oleksandr Byelkin <sanja@xxxxxxxxxxxx>]

Hi!

On 07.09.2010 17:49, Sergei Golubchik wrote:
> Hi, Sanja!
>
> On Sep 07, sanja@xxxxxxxxxxxx wrote:
>    
> > At file:///home/bell/maria/bzr/work-maria-5.3-lb615760/
> >
> > ------------------------------------------------------------
> > revno: 2816
> > revision-id: sanja@xxxxxxxxxxxx-20100907061732-yyuwtfg0ucyqiu8j
> > parent: sanja@xxxxxxxxxxxx-20100906123424-2sco3ghittvidm6l
> > committer: sanja@xxxxxxxxxxxx
> > branch nick: work-maria-5.3-lb615760
> > timestamp: Tue 2010-09-07 09:17:32 +0300
> > message:
> >    Fixed second part of the LP BUG#615760 - incorrect parameters of the
> >    temporary heap table index (unique&  nulls are equal).
> >      
>    
> > === modified file 'sql/sql_expression_cache.cc'
> > --- a/sql/sql_expression_cache.cc	2010-09-06 12:34:24 +0000
> > +++ b/sql/sql_expression_cache.cc	2010-09-07 06:17:32 +0000
> >      
> I cannot review that change, I don't know sql_expression_cache code :(
> Anyway, you asked me to look at the "incorrect heap table index flags"
> changes only.
>
>    
> > === modified file 'sql/table.cc'
> > --- a/sql/table.cc	2010-07-10 10:37:30 +0000
> > +++ b/sql/table.cc	2010-09-07 06:17:32 +0000
> > @@ -5191,7 +5191,7 @@
> >     keyinfo->usable_key_parts= keyinfo->key_parts = key_parts;
> >     keyinfo->key_length=0;
> >     keyinfo->algorithm= HA_KEY_ALG_UNDEF;
> > -  keyinfo->flags= HA_GENERATED_KEY;
> > +  keyinfo->flags= HA_GENERATED_KEY | HA_NOSAME;
> >     sprintf(buf, "key%i", key);
> >     if (!(keyinfo->name= strdup_root(&mem_root, buf)))
> >       return TRUE;
> > @@ -5230,6 +5230,7 @@
> >       {
> >         key_part_info->store_length+= HA_KEY_NULL_LENGTH;
> >         keyinfo->key_length+= HA_KEY_NULL_LENGTH;
> > +      keyinfo->flags|= HA_NULL_ARE_EQUAL;	// def. that NULL == NULL
> >       }
> >       if ((*reg_field)->type() == MYSQL_TYPE_BLOB ||
> >           (*reg_field)->real_type() == MYSQL_TYPE_VARCHAR)
> >      
> Difficult to say.
>
> Sure, temporary tables should have keyinfo->flags=HA_NOSAME and
> keyinfo->flags|= HA_NULL_ARE_EQUAL. You can see that in
> create_tmp_table(). HA_GENERATED_KEY has no effect, so it doesn't matter
> if you specify it or not.
>
> But I don't know what are requirements for temporary tables in your
> subquery cache code.
>    

I need unique index on almost all fields (actually primary index).

> Unrelated question - why did you duplicate creation of temporary
> tables? I understand that you may've needed something slightly different
> from create_tmp_table(), but then you should've changed
> create_tmp_table() to use your new code, TABLE::add_tmp_key() etc.
>    
The function is not mine, and it is made by Evgen in 6.0 then redone by 
Igor, and here is good point, AFAIK Igor will need not only unique 
indeces for his tables.
> By the way, if you had done that (reused the code, not duplicated it)
> this bug would've been impossible - many tests in the test suite would
> fail at once if all temporary tables would have non-unique indexes.
>    
Everything we have in create_tmp_table is not suitable for my task and 
especially for Igor task. He creates all possible useful indeces over 
temporary table which, then drop unneeded and use only suitable for join 
optimisation. So it could not be done in one function, and need several 
calls to add index by index.

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