[Monetdb-developers] Re: [MonetDB-users] speed comparison off inserts and deletes, and db size question

Fabian Fabian.Groffen at cwi.nl
Wed Aug 3 12:56:45 CEST 2005


I don't have enough in-depth knowledge to answer these questions.  I ope 
someone else has the time to give you the right answers.

Joel Reymont wrote:
> On Aug 3, 2005, at 10:40 AM, Fabian wrote:
> 
>> You should keep in mind that if you use a (V)OID on an 32-bits  
>> platform, that you have a limitation of the number of rows that you  
>> can contain in a BAT.  Also, and OID cannot be bigger than the int  it 
>> is, so if you do need more rows, or sequence numbers that are  higher, 
>> you will have to jump over to lng and do the sequence  numbers 
>> yourself or something.
>>
> 
> Is it 2^32-1 for the maximum number of rows in a BAT?
> 
> 
>> You can never join BATs that are bigger than max(OID), so you have  to 
>> play tricks like doing the selects on all it's subparts and then  
>> unioning the results, given they are small enough to be stored in  one 
>> BAT.
>>
> 
> Are you referring to BAT * BATkunion (BAT *b, BAT *c) in the kernel  guide?
> 
> I assume that I need to use BATkunion as opposed to BATsunion since  I'm 
> looking only at the head column. And that the fragments satisfy  the set 
> property since they are fragments of a larger BAT with a non- repeating 
> oid range. Am I thinking right?
> 
> Do I need to set any properties on the BAT for the union to work?
> 
>     Thanks, Joel
> 
> -- 
> http://wagerlabs.com/uptick
> 
> 
> 
> 




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