On Sat, Oct 31, 2015 at 1:32 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > On Thu, Oct 8, 2015 at 11:05 PM, Simon Riggs <si...@2ndquadrant.com> wrote: >> >> On 1 October 2015 at 23:30, Josh Berkus <j...@agliodbs.com> wrote: >>> >>> On 10/01/2015 07:43 AM, Robert Haas wrote: >>> > On Thu, Oct 1, 2015 at 9:44 AM, Fujii Masao <masao.fu...@gmail.com> >>> > wrote: >>> >> I wonder how much it's worth renaming only the file extension while >>> >> there are many places where "visibility map" and "vm" are used, >>> >> for example, log messages, function names, variables, etc. >>> > >>> > I'd be inclined to keep calling it the visibility map (vm) even if it >>> > also contains freeze information. >>> > > > What is your main worry about changing the name of this map, is it > about more code churn or is it about that we might introduce new issues > or is it about that people are already accustomed to call this map as > visibility map?
My concern is mostly that I think calling it the "visibility and freeze map" is excessively long and wordy. One observation that someone made previously is that there is a difference between "all-visible" and "index-only scan OK". An all-visible page that has a HOT update is no longer all-visible (it needs vacuuming) but an index-only scan would still be OK (because only the non-indexed values in the tuple have changed, and every scan scan can see either the old or the new tuple but not both. At present, the index-only scan will consult the heap page anyway, because all we know is that the page is not all-visible. But maybe in the future somebody will decide to add a bit for that. Then we'd have the "visibility, usable for index-only scans, and freeze map", but I think "_vufiosfm" will not be a good choice for a file suffix. So similarly here. The file suffix doesn't need to enumerate all the bits that are present for each page. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
