[Monetdb-developers] hashing algorithms usage in MonetDB/Five

Martin Kersten Martin.Kersten at cwi.nl
Fri Apr 28 23:33:38 CEST 2006


Fabian, FYI

Starting the server takes 0.032 sec for M4 and 0.056 for M5 on
my machine.
Connection to the server using MapiClient takes 0.009 sec for M5
and using mjclient before rolling forward to hashes on M5 takes ~0.150 sec.

This puts the overhead of connecting using the challenges
in a different perspective.

Fabian Groffen wrote:
> Hi all, FYI
> 
> Sourceforge isn't really cooperating, but I implemented MD5 and SHA1
> hash algorithms support during challenge response in MAPI.  I extended
> the JDBC driver to be able to use SHA1 or MD5 next to plain (crypt is
> not easily available in Java).  I will check in my changes as soon as
> 1) SourceForge lets me, and
> 2) My physical state + location lets me
> 
> I also added a little option to JdbcClient to force usage of a specified
> hash algorithm, using -Xhash.  I conducted a little experiment to see
> the effect of connecting with a hash or plain.  The results for my system is as follows:  (I ran every call 10 times and took the average)
> 
> % time java -jar jars/jdbcclient-1.4.jar -Xhash SHA1 < /dev/null
> real 0.29
> % time java -jar jars/jdbcclient-1.4.jar -Xhash MD5 < /dev/null
> real 0.29
> % time java -jar jars/jdbcclient-1.4.jar -Xhash plain < /dev/null
> real 0.23
> 
> The precision of time is seconds here, so the difference in time (or the
> cost of both hash implementations) is 0.06 seconds.  This includes the
> time for the server to do the same of course.  All in all, not really
> shocking IMHO.  Please note that the JdbcClient does a lot of other
> stuff like querying the database for its version number and such.  When
> not doing that the time will be probably lower.  Also, the wallclock
> time does also include the full JVM startup.  The C implementation of
> the hashes might be more efficient, I can only tell something useful
> about that once MapiClient will also support hash algorithms.
> 
> 
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