On Tue, Nov 3, 2015 at 6:37 AM, Simon Riggs <si...@2ndquadrant.com> wrote:
> On 3 November 2015 at 15:23, Amit Kapila <amit.kapil...@gmail.com> wrote:
>> On Fri, Oct 23, 2015 at 6:29 AM, Simon Riggs <si...@2ndquadrant.com>
>> wrote:
>>> On 21 October 2015 at 13:31, Jeff Janes <jeff.ja...@gmail.com> wrote:
>>>> Index-only scans will visit the heap for each tuple until the first
>>>> VACUUM is done.
>>>> The first vacuum will read the entire table, but not need to write it
>>>> anymore.  And will create the _vm file.
>>>> I think we really want to create _vm file as well as set PD_ALL_VISIBLE,
>>>> but I don't know the best way to do that.  Set a flag somewhere and then
>>>> create it in bulk at the end of the transaction?  Set it bit by bit as the
>>>> pages are extended and initialized?
>>> Easy enough to do it at the end of the COPY FREEZE in one step.
>> Here, we might want to consider that setting bit in visibility map
>> will generate WAL log whereas Copy Freeze otherwise skip WAL
>> when wal_level is less than archive.  This can lead to extra disk
>> writes which can slow down Copy Freeze, but OTOH that might
>> be acceptable.
> I'm building the map as I go, in the latest version of this patch I'm
> working on.

Hi Simon,

Is this still on your radar?  If you would like someone else to pick
it up, can you post the WIP patch you have?



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