mnesia query

Sebastian Bello <>
Fri Jul 22 19:04:03 CEST 2005

I've done some test with indexes and am a bit confused.
I've ran the same query using select, index_read and QLC and performance
seems to follow that same order(faster to slower). I noted that performance
depedends on the number of records associated to the value of the index
searched. There's surely something I'm missing here. My questions would be:
1. shouldn't performance be better for index_read and QLC than select (since
an index is beeing used)?
2. when using QLC, should indexes be used explicitly (or just write a normal
list comprehension query)?
3. depending on 2, how can I use two indexes with QLC?
4. just to be sure, should a search through two indexes be always faster
than using just one?

I saw some old questions regarding this point, but didn't get a clear idea
about it.

----- Original Message -----
From: "Ulf Wiger" <>
To: "Sebastian Bello" <>; <>
Sent: Sunday, July 17, 2005 11:19 AM
Subject: Re: mnesia query

> Den 2005-07-17 15:26:43 skrev Sebastian Bello <>:
> > But is it possible to use mnesia:index_match_object() with two indexes?
> >     Sebastian-
> No. You specify exactly _one_ index that index_match_object() is to use.
> /Uffe

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