| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Jakub Wartak <jakub(dot)wartak(at)enterprisedb(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, MARK CALLAGHAN <mdcallag(at)gmail(dot)com>, Tomas Vondra <tomas(at)vondra(dot)me> |
| Subject: | Re: Problems with get_actual_variable_range's VISITED_PAGES_LIMIT |
| Date: | 2026-09-15 16:01:17 |
| Message-ID: | CAH2-Wz=J2d3TFJ1QLTia5Hr-kJXk+URBT8h10vGi6hO82L3kjw@mail.gmail.com |
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On Tue, Jun 23, 2026 at 4:06 PM Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> Importantly, this allows VISITED_PAGES_LIMIT to work exactly the same
> way on standbys as it does today. During hot standby, LP_DEAD bits
> cannot be set or used to avoid heap fetches. As long as each leaf page
> returns at least one match (which could still be a TID pointing to a
> dead heap tuple), nothing changes -- INDEX_PAGES_LIMIT does nothing
> new, we rely on VISITED_PAGES_LIMIT in the traditional way.
I attach this patch here, to be tracked as its own CF entry going forward.
I committed "Add slot-based table AM index scan interface" this
morning, which this INDEX_PAGES_LIMIT patch depends on. There's no
longer any reason to tie this patch to the index
prefetching/amgetbatch work.
--
Peter Geoghegan
| Attachment | Content-Type | Size |
|---|---|---|
| v1-0001-Limit-get_actual_variable_range-leaf-page-reads.patch | application/octet-stream | 7.6 KB |
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