SELECT DISTINCT on datatype inet causes high load even after cancelling
Good day,
We're experiencing a phenomenon that I can't quite explain.
We have a table of maybe 110M entries mapping IP addresses to some values. The data type of field ip_addr is net. No indices or constraints set.
A SELECT COUNT(ip) is zippy - result in some ms. Any SELECT, in fact, that does not use WHERE is fast. E.g.:
SELECT ip, result FROM iptable LIMIT 10000; +------------------ 10000 tuples (4.6s)
However: A SELECT COUNT(DISTINCT ip) does not return even after waiting an hour or, just to try it out once, 24 hrs. Load remained at 27 during that time. I restarted the server after that, as I had done ctrl-c in mclient, and that seems to let the current query continue? What would be the right way to cancel a query?
I then tried SELECT ip FROM iptable WHERE ip = inet '1.0.0.1'
That IP is the second in the column. The query did not return even after 10 minutes. That seems a bit excessive.
Does anyone have a clue why this is so? Should I avoid inet?
Thanks, Ralph
Disclaimer: I come from a psql background and these are my first steps with vertical-col data stores.
Server:
MonetDB 5 server v11.15.11 "Feb2013-SP3" (64-bit, 64-bit oids) Copyright (c) 1993-July 2008 CWI Copyright (c) August 2008-2013 MonetDB B.V., all rights reserved Visit http://www.monetdb.org/ for further information Found 142.0GiB available memory, 24 available cpu cores Libraries: libpcre: 8.30 2012-02-04 (compiled with 8.02) openssl: OpenSSL 0.9.8o 01 Jun 2010 (compiled with OpenSSL 0.9.8o 01 Jun 2010) libxml2: 2.7.8 (compiled with 2.7.8) Compiled by: root@dev.monetdb.org (x86_64-pc-linux-gnu) Compilation: gcc -O3 -fomit-frame-pointer -pipe -Wp,-D_FORTIFY_SOURCE=2 Linking : /usr/bin/ld -m elf_x86_64
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Ralph Holz