| From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
|---|---|
| To: | Tatsuo Ishii <ishii(at)postgresql(dot)org> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Too many IO? |
| Date: | 2012-03-14 08:28:30 |
| Message-ID: | CA+U5nMJf+QB8_jzrniHF5Xv7fz2y1Q8pt3-8aPbkrOaia6w8yA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Mar 14, 2012 at 2:29 AM, Tatsuo Ishii <ishii(at)postgresql(dot)org> wrote:
> However I saw 1505 more accesses in total. My guess is this number
> mainly comes from index meta page access. So my guess is we need 3
> page accesses (to traverse b tree index tree) before reaching the leaf
> page in average. Am I correct or the number is execessive?
Meta page access was optimised away some time ago.
Descending the index tree can easily take that long, perhaps longer
when the table is larger and the tree is deeper.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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