Horton

Re: RFC: Making TRUNCATE more "MVCC-safe"

Simon Riggs <simon@2ndquadrant.com>

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From: Simon Riggs <simon@2ndQuadrant.com>
To: Marti Raudsepp <marti@juffo.org>
Cc: Noah Misch <noah@leadboat.com>, Kevin Grittner <Kevin.Grittner@wicourts.gov>, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2012-03-04T16:39:58Z
Lists: pgsql-hackers

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On Sun, Mar 4, 2012 at 1:02 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On Sun, Mar 4, 2012 at 9:59 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> On Sun, Mar 4, 2012 at 2:28 AM, Marti Raudsepp <marti@juffo.org> wrote:
>>> On Sat, Mar 3, 2012 at 14:53, Simon Riggs <simon@2ndquadrant.com> wrote:
>>>> Thanks Noah for drawing attention to this thread. I hadn't been
>>>> watching. As you say, this work would allow me to freeze rows at load
>>>> time and avoid the overhead of hint bit setting, which avoids
>>>> performance issues from hint bit setting in checksum patch.
>>>>
>>>> I've reviewed this patch and it seems OK to me. Good work Marti.
>
> ...
>
>> v3 attached.
>
> More detailed thoughts show that the test in heap_beginscan_internal()
> is not right enough, i.e. wrong.
>
> We need a specific XidInMVCCSnapshot test on the relvalidxid, so it
> needs to be a specific xid, not an xmin because otherwise we can get
> concurrent transactions failing, not just older transactions.

Marti, please review this latest version which has new isolation tests added.

This does both TRUNCATE and CREATE TABLE.

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
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