| From: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Indirect indexes |
| Date: | 2016-10-18 21:21:08 |
| Message-ID: | CAPpHfdv6UGDBjkm+ZKQNZvD9+rQTqT5dCyWqjmBEwL3J6E_GgA@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi, Alvaro!
Thank you for your proposal. One question about vacuum excites me most.
On Tue, Oct 18, 2016 at 9:28 PM, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
wrote:
> Vacuuming presents an additional challenge: in order to remove index
> items from an indirect index, it's critical to scan the PK index first
> and collect the PK values that are being removed. Then scan the
> indirect index and remove any items that match the PK items removed.
> This is a bit problematic because of the additional memory needed to
> store the array of PK values. I haven't implemented this yet.
>
Imagine another situation: PK column was not updated, but indirect indexed
column was updated.
Thus, for single heap tuple we would have single PK tuple and two indirect
index tuples (correct me if I'm wrong).
How are we going to delete old indirect index tuple?
------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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