Re: [ROOT] TSQLServer.Query() : buffer size limit? timeout?

From: Dr. John Krane (jkrane@fnal.gov)
Date: Wed Jul 09 2003 - 19:27:35 MEST


Thanks Fons,

I have put in a 1GB swap area and ran over 4.2M events successfully.  I 
am now trying 58M events...

    - John

Fons Rademakers wrote:

>Hi John,
>
> the  current version of the MySQL interface reads the complete result
>set from the DB server into the client memory, so you must have enough
>RAM and swap.
>
>Cheers, Fons.
>
>
>On Tue, 2003-07-08 at 21:15, Dr. John Krane wrote:
>  
>
>>Hi,
>>
>>I need to run over many millions of events in an SQL database.  From the
>>way my tree-making code is behaving, it looks like TSQLServer.Query()
>>pulls over all the information at once and stores it in memory, then my
>>code runs over the TSQLResult from that memory.  It is unclear to me if 
>>the memory is disk-resident but I think it must be.
>>
>>Is there some buffer size limit or is this TSQLResult written to an
>>intermediate file or ???  I'm really having difficulty with my system 
>>freezing if I request more than 3 million events.  Less than 3M and I do 
>>not freeze.  Could somebody please explain how TSQLServer.Query handles 
>>large results?  My disk drive is enormous so I really can't run out of 
>>disk space if I am allowed to define a buffer area.  I might be in 
>>trouble if it is hard-wired to /tmp on my Linux box.
>>
>>	- John
>>    
>>



This archive was generated by hypermail 2b29 : Thu Jan 01 2004 - 17:50:13 MET