Hi All - can someone help me clarify the difference between Algebra
"-G" mode and setting SQL debug equal to 16384 in the monetdb config
file?
With an older version of MonetDb I set the sql_debug=16384 in the
config file so I could take advantage of Algebra mode when starting the
server via mero.
Today I compiled the Nov08-SP2 release and ran some tests using
sql_debug=0 vs sql_debug=16384. I assumed they would do the exact same
since Algebra mode is now the default. They returned very different
results however.
For SQL statements with a large number of predicates (100+),
performance is about the same. But for anything smaller the query speed
is much worse (10x avg) when I don't have sql_debug=16384 turned on.
The
query trace files are also different when I run the exact same query with and without the 16384 flag. I made sure to restart the server process in between.
Also, below is the latest output from mserver --version:
Copyright (c) 1993-July 2008 CWI
Copyright (c) August 2008- MonetDB B.V., all rights reserved
Visit http://monetdb.cwi.nl/ for further information
Configured for prefix: /home/ross/monetNov08sp2
Libraries:
openssl: OpenSSL 0.9.8g 19 Oct 2007 (compiled with OpenSSL 0.9.8g 19 Oct 2007)
Compiled by: ross@home
Compilation: gcc -O2 -std=c99 -fgnu89-inline -O6 -fomit-frame-pointer
-finline-functions -falign-loops=4 -falign-jumps=4 -falign-functions=4 -fexpensive-optimizations
-funroll-loops -frerun-cse-after-loop -frerun-loop-opt -ftree-vectorize
Linking : /usr/bin/ld
Any thoughts?
Best Regards,
Ross