| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Gordon Shannon <gordo169(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Surprising dead_tuple_count from pgstattuple |
| Date: | 2010-08-09 18:21:45 |
| Message-ID: | AANLkTi=Hq+Xtkm0hqyST32RuwSum-SDuM6DjOy8vmKGQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, Aug 9, 2010 at 1:50 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Sat, 2010-08-07 at 16:11 -0700, Gordon Shannon wrote:
>
>> So, I guess my real question here is, what happened to the "missing"
>> 100 items? If it was HOT prune, can anyone summarize what that does?
>
> Itagaki already explained that the second DELETE would have removed the
> 100 dead rows you consider to be missing.
>
> Any SQL statement that reads a block can do HOT pruning, if the block is
> otherwise unlocked.
Where does heap_page_prune() get called from in the DELETE path?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company
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