Hi Sam, On Mon, May 17, 2010 at 01:07:50PM +0100, Sam Mason wrote:
Hi,
I've just pulled a largish dataset into monetdb (419851473 rows, 8 columns) and it's crashing when I try to do the following:
does the server carsh, or does it "merely" issue an error on this query, but the server keep running? Indeed, it should not even need to give the error, but it surely should not crash ...
select count(distinct a) from calldata;
"a" is an integer column and monetdb gets the right answer of 886693 when I run either:
select count(a) from (select a from calldata group by a) x; or select count(a) from (select distinct a from calldata) x;
I'm running the latest 64bit .deb packages under ubuntu 10.4. The following is what I get back from mclient:
Just for info: did you try with earlier versions before? If so, did it work? (You don't have to try it, if you didn't ...)
sql>select count(distinct a) from calldata; MALException:!ERROR: HEAPalloc: Insufficient space for HEAP of 3358812160 bytes. ERROR: HEAPalloc: Insufficient space for HEAP of 3358812160 bytes. ERROR: HEAPalloc: Insufficient space for HEAP of 3358812160 bytes. Timer 93948.763 msec 1 rows
I've not got much swap space, does it just happen to need it for the first version but not the other versions?
It should not use swap space, but memory mapped files, i.e., disk space in your file system where your dbfarm is located. And indeed, if the two aboe version work, than also the count(distinct ..) should work --- possibly some yet undetected glitch in the query translation / optimization --- you can check the PLAN or EXPLAIN of all three variant to see whether/how they differ. We'll try to do the same (without your data) to see what we can find ... Stefan
-- Sam http://samason.me.uk/
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