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To: "Stefan Keller" <sfkeller@gmail.com>
Cc: mmoncure@gmail.com, pgsql-performance@postgresql.org, "Robert Haas"
	<robertmhaas@gmail.com>
Subject: Re: FW: KVP table vs. hstore - hstore performance (Was:
	Postgres NoSQL emulation)
References: <BANLkTi=LjFTnn8hLwBZc1c87Vq+pw02+jQ@mail.gmail.com>
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	<BANLkTimdGR4X0uMMyMwtvy9Uex-zeMtVCQ@mail.gmail.com>
	<BANLkTintNbJZw-hnVpy8q5jLW1__E9BY1w@mail.gmail.com>
	<99EECF01B5C87A498318776AB7E4A78D3640F59E26@sid00102.hsr.ch>
	<op.vvxkj7o8eorkce@apollo13>
	<BANLkTimiphaS_5yBLjr-jDPFjWV3Uc1etA@mail.gmail.com>
	<op.vv1qt1fdeorkce@apollo13>
	<BANLkTiknLoZMjV8eY6cdwwdXKb0jxgKP4w@mail.gmail.com>
Date: Thu, 26 May 2011 11:24:24 +0200
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From: "Pierre C" <lists@peufeu.com>
Message-ID: <op.vv20eyc1eorkce@apollo13>
In-Reply-To: <BANLkTiknLoZMjV8eY6cdwwdXKb0jxgKP4w@mail.gmail.com>
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> My problem is, that in fact I don't know which tag to index since I'm
> running a web admin application where users can enter arbitrary
> queries.

For a tag cloud, try this :

- table tags ( tag_id, tag_name )
- table articles ( article_id )
- table articles_to_tags( article_id, tag_id )

now this is the classical approach, which doesn't work so well when you  
want to get an article that has several tags (tag intersection).

So, materialize the list of tag_ids for each article in an INTEGER[] array  
in the articles table, kept up to date with triggers.

Create a gist index on that, and use indexed array vs array operators.