Re: [Patch] Temporary tables that do not bloat pg_catalog (a.k.a fast temp tables)

On Wed, Aug 24, 2016 at 2:04 AM, Alvaro Herrera
<alvherre@2ndquadrant.com> wrote:
> Claudio Freire wrote:
>
>> After looking at it from a birdseye view, I agree it's conceptually
>> complex (reading HeapTupleSatisfiesSelf already makes one dizzy).
>>
>> But other than that, the implementation seems rather simple. It seems
>> to me, if one figures out that it is safe to do so (a-priori, xmin not
>> committed, xmax is current transaction), it would simply be a matter
>> of chasing the HOT chain root, setting all LP except the first to
>> LP_UNUSED and the first one to LP_DEAD.
>>
>> Of course I may be missing a ton of stuff.
>
> What you seem to be missing is that rows corresponding to temp tables
> are not "visible to its own transaction only".  The rows are valid
> after the transaction is gone; what makes the tables temporary is the
> fact that they are in a temporary schema.  And what makes them invisible
> to one backend is the fact that they are in the temporary schema for
> another backend.  Not that they are uncommitted.

Yeah, I was thinking of "on commit drop" behavior, but granted there's
all the others.