| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, "Jonah H(dot) Harris" <jonah(dot)harris(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Improving count(*) |
| Date: | 2005-11-17 22:37:19 |
| Message-ID: | 20234.1132267039@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> Now, lets say you add a field to the tuple which you the position of
> the index entry. You can only reasonably do this for one index, say the
> primary key. Now you have a two-way link the updating becomes much
> quicker, at the cost of even more overhead.
I think this is fairly infeasible --- consider what it does to the cost
and (lack of) atomicity of an index page split, for instance.
regards, tom lane
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