On 6/24/06, Mark Woodward <[EMAIL PROTECTED]> wrote:
Currently it looks like this:


That's what t_ctid does now, right? Well, that's sort of stupid. Why not
have it do this:


Heh, because that's crazy.  The first time you insert a key into the
index it will point to v1 of a tuple... say after 5 updates you have
v2,v3,v4,v5... your c_tid pointer chain looks like v1
(original)->v2->v3->v4-v5 (newest).  However, your whole idea is based
on not having to do another index insert for unchanged keys, so the
index still points to v1... which means you have to follow the c_tid
chain to get to the newest version just like a sequential scan.  I
don't see how you think you can reverse pointer it.

This will speed up almost *all* queries when there are more than two
version of rows.


When you vacuum, simply make the latest version (verN) the key row (ver001).

How are you going to do this without a ton of locking... remember, the
index is pointing to v1 with a tid... so you'll have to physically
move the newest version v5 to v1's tid from wherever it was... like a
vacuum full on steroids.  Unless of course, you rebuild the index...
but that's not a solution either.

Jonah H. Harris, Software Architect | phone: 732.331.1300
EnterpriseDB Corporation            | fax: 732.331.1301
33 Wood Ave S, 2nd Floor            | [EMAIL PROTECTED]
Iselin, New Jersey 08830            | http://www.enterprisedb.com/

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