The behavior was observed using
MonetDB5-SQL-Installer-i386-20071120.msi running on Windows XP SP 2.
On Nov 24, 2007 12:56 AM, Markus Gritsch
Hi,
I have a medium sized dataset of about 50 MB text data. When I repeatedly call
SELECT * FROM entry WHERE LOWER(note) LIKE '%hui%'
I get at some time not my result, but the following error in DbVisualizer:
protocol violation, unexpected line: VirtualAlloc(1a0a0000,29806592,MEM_COMMIT,PAGE_READWRITE): failed
Repeatedly calling the query from the command line like this
mclient.exe -lsql -s"SELECT * FROM entry WHERE LOWER(note) LIKE '%hui%'" > result.txt
produces the attached memory usage graph. After 11 times calling the query the memory is full, and some kind of garbage collection seems to happen. However, after only 6 additional times the memory is again full and the garbage collection is quite less effective than before. Subsequent calls reach the memory limit every time.
Markus
P.S.: I have disabled the virtual memory on my Windows XP because when the OS starts paging, it becomes unbearably slow.