Re: Reviewing freeze map code - Mailing list pgsql-hackers

From Andres Freund
Subject Re: Reviewing freeze map code
Date
Msg-id 20160630034317.r7axkleum65u6t2l@alap3.anarazel.de
Whole thread Raw
In response to Re: Reviewing freeze map code  (Amit Kapila <amit.kapila16@gmail.com>)
Responses Re: Reviewing freeze map code
List pgsql-hackers
On 2016-06-30 08:59:16 +0530, Amit Kapila wrote:
> On Wed, Jun 29, 2016 at 10:30 PM, Andres Freund <andres@anarazel.de> wrote:
> > On 2016-06-29 19:04:31 +0530, Amit Kapila wrote:
> >> There is nothing in this record which recorded the information about
> >> visibility clear flag.
> >
> > I think we can actually defer the clearing to the lock release?
> 
> How about the case if after we release the lock on page, the heap page
> gets flushed, but not vm and then server crashes?

In the released branches there's no need to clear all visible at that
point. Note how heap_lock_tuple doesn't clear it at all. So we should be
fine there, and that's the part where reusing an existing record is
important (for compatibility).

But your question made me realize that we despearately *do* need to
clear the frozen bit in heap_lock_tuple in 9.6...

Greetings,

Andres Freund



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