filtering functions in mnemosyne

Hakan Mattsson <>
Wed Nov 28 23:06:57 CET 2001


On Wed, 28 Nov 2001, Laszlo Varga wrote:

Laszlo>Date: Wed, 28 Nov 2001 17:17:45 +0100 (MET)
Laszlo>From: Laszlo Varga <>
Laszlo>To: 
Laszlo>Subject: filtering functions in mnemosyne
Laszlo>
Laszlo>Hi Sirs,
Laszlo>
Laszlo>sorry for this newby question. I'm just playing around with mnesia,
Laszlo>and has found something which shurely possible but I couldn't get through.
Laszlo>
Laszlo>What I want, is to use a function in a query like this (simplified)
Laszlo>    
Laszlo>isTheSame({A,A}) -> true;
Laszlo>isTheSame(B) -> false.  
Laszlo>
Laszlo>for cheking the records.
Laszlo>
Laszlo>What I get: 
Laszlo>{aborted,{badarg,{ets,lookup,[db_get,[mnemosyne_catalog,{image,foo}]]}}}

This was not the most pedagogic error message that I have seen.
Try application:start(mnemosyne) and see if the error persists.

Btw, the new select function in Mnesia is much more efficient than
Mnemosyne. Not as elegant as the Mnemosyne queries, but blinding fast.

/Håkan

---
Håkan Mattsson
Ericsson
Computer Science Laboratory
http://www.ericsson.com/cslab/~hakan/




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