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<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2>Hi Edwin,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2>Thanks and good idea - I am actually investigating that
route right this moment!</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2>I think I could definitely do it, the problem being that
after an initial bootstrap of the Mnesia tables I will be in a situation where I
will be receiving live/real-time updates to the data. These unfortunately will
need to be reflected in mnesia so that the queries performed against it are
fully up-to-date whilst still enabling real-time response rates to the queries
themselves.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2>A bit of a mouthful I know!</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2>Many Thanks,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=571534716-30092008><FONT face=Arial
color=#0000ff size=2>Dan</FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> emofine@gmail.com
[mailto:emofine@gmail.com] <B>On Behalf Of </B>Edwin Fine<BR><B>Sent:</B> 30
September 2008 17:48<BR><B>To:</B> RUBINO, Dana, GBM<BR><B>Cc:</B>
taavi@uninet.ee; erlang-questions@erlang.org<BR><B>Subject:</B> Re:
[erlang-questions] Extremely poor Mnesia performance<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV dir=ltr>Is it possible to denormalize the data so that you don't have so
many tables? Mnesia can behave as a hierarchical database because you can store
arbitrarily complex terms, including what amounts to trees (lists of tuples of
lists of.....). If your queries are likely to remain the same over time and you
don't need ad-hoc queries, could you consider this approach? The problem with
any hierarchy, of course, is that if you get it wrong it can be hell on wheels
to fix.<BR><BR>
<DIV class=gmail_quote>On Tue, Sep 30, 2008 at 12:23 PM, <SPAN dir=ltr><<A
href="mailto:Dana.RUBINO@rbs.com">Dana.RUBINO@rbs.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE class=gmail_quote
style="PADDING-LEFT: 1ex; MARGIN: 0pt 0pt 0pt 0.8ex; BORDER-LEFT: rgb(204,204,204) 1px solid">Thanks
Taavi,<BR><BR>That wasn't the answer I was looking for! :-D<BR><BR>Oh dear,
well that leaves my plan for using Mnesia in tatters.<BR><BR>I actually need
an in memory db which at least has the core subset of RDBMS features. So I am
essentially just looking for a small in memory DB for real-time
access.<BR><BR>Has anyone here had any experience using something like KDB
with Erlang?<BR><BR>Perhaps I could switch to using KDB as an
alternative?<BR><BR>Many Thanks,<BR>Dan<BR>
<DIV>
<DIV></DIV>
<DIV class=Wj3C7c><BR>-----Original Message-----<BR>From: Taavi Talvik
[mailto:<A href="mailto:taavi@uninet.ee">taavi@uninet.ee</A>]<BR>Sent: 30
September 2008 17:19<BR>To: RUBINO, Dana, GBM<BR>Cc: <A
href="mailto:erlang-questions@erlang.org">erlang-questions@erlang.org</A><BR>Subject:
Re: [erlang-questions] Extremely poor Mnesia performance<BR><BR><BR>On Sep 30,
2008, at 5:58 PM, <<A
href="mailto:Dana.RUBINO@rbs.com">Dana.RUBINO@rbs.com</A>>
wrote:<BR><BR>><BR>> Hey all,<BR>><BR>> I am doing some
benchmarking with Mnesia at the moment and am pretty<BR>> disappointed to
say the least.<BR>><BR>> I'm hoping I am doing something
wrong.<BR>><BR>> Running a 5 table join below: (two of the tables have
~50k rows the<BR>> rest a couple of hundred)<BR><BR>Probably you are not
doing anything wrong. From mnesia introduction (<A
href="http://www.erlang.org/doc/apps/mnesia/Mnesia_chap1.html#1"
target=_blank>http://www.erlang.org/doc/apps/mnesia/<BR>Mnesia_chap1.html#1</A>),<BR>it
design goals are:<BR>===<BR>In telecommunications applications there are
different needs from the features provided by traditional DBMSs. The
applications now implemented in the Erlang language need a mixture of a broad
range of features, which generally are not satisfied by traditional
DBMSs.<BR>Mnesia is designed with requirements like the following in
mind:<BR><BR> * Fast real-time key/value
lookup<BR> * Complicated non real-time queries
mainly for operation and maintenance<BR> *
Distributed data due to distributed applications<BR>
* High fault tolerance<BR> * Dynamic
re-configuration<BR> * Complex
objects<BR>===<BR><BR>Mnesia is not designed as replacement for relational
database. It is optimised for fast key-value lookup and
distribution.<BR><BR>With qlc:info(Qh) you can get more information, how query
is actually handled.<BR><BR>best regards,<BR>taavi<BR><BR></DIV></DIV>
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