6 Dec
2011
6 Dec
'11
3:53 p.m.
Hi,
I'm observing disk I/O when evaluating some queries which I am unable to explain. I have two datasets, one relatively small with the BATs taking up 1.6 MB on disk and one fairly large with 283 MB on disk.
According to iostat, when I evaluate the attached query on the small dataset, 100 MB are written to disk, but none are read. This is on a Linux machine with 4 GB RAM running the Aug2011-SP3 release.
I don't understand why data is written on disk, that
(a) is never read again and (b) would easily fit into main memory.
I am unable to evaluate the queries on the large dataset because MonetDB writes so much data that the disk fills up after a few minutes (more than 22GB).
Please let me know if I can provide more information.
Cheers, Viktor