From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com> |
Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: optimizing vacuum truncation scans |
Date: | 2015-07-27 22:32:53 |
Message-ID: | 55B6B195.9090601@BlueTreble.com |
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Lists: | pgsql-hackers |
On 7/27/15 10:39 AM, Robert Haas wrote:
> But that's not enough: we also need to know that any tuple that
> survived the prune operation (that is, it wasn't redirected or marked
> unused) has a new-enough xmin, which isn't tracked anywhere.
Wouldn't that be old-enough xmin?
heap_prune_chain() is already calling HeapTupleSatisfiesVacuum, so it
should be able to figure out if the page is all visible without a lot of
extra work, and pass that info back to heap_page_prune (which would then
pass it down to _execute()).
Definitely not a one-liner though.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Data in Trouble? Get it in Treble! http://BlueTreble.com
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