Re: HOT patch - version 15

"Tom Lane" <tgl@sss.pgh.pa.us> writes:

> Bruce Momjian <bruce@momjian.us> writes:
>> Tom Lane wrote:
>>> Uh, why would any of this code at all execute during a pure lookup?
>
>> No idea.  It seems an index lookup tries to prune a heap chain, and he
>> was asking if it should look at other chains on the page;  I said not.
>> Whether the index lookup should prune the heap chain is another issue.
>
> ISTM the only time we should be doing HOT cleanup work is when we are
> trying to insert a new tuple on that page --- and maybe even only when
> we try and it doesn't fit straight off.  Otherwise you're pushing
> maintenance work into foreground query pathways, which is exactly where
> I don't think we should be headed.

Ah, as I understand it you can't actually do the pruning then because the
executor holds references to source tuple on the page. In other words you can
never "get the vacuum lock" there because you already have the page pinned
yourself.

--
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com