Re: ALTER TABLE lock strength reduction patch is unsafe

Simon Riggs <simon@2ndquadrant.com>

From: Simon Riggs <simon@2ndQuadrant.com>
To: Noah Misch <noah@leadboat.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Bruce Momjian <bruce@momjian.us>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2012-01-02T18:41:31Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →
  1. Add bytea_agg, parallel to string_agg.

  2. Fix ALTER TABLE ONLY .. DROP CONSTRAINT.

On Mon, Jan 2, 2012 at 6:06 PM, Noah Misch <noah@leadboat.com> wrote:
> On Mon, Jan 02, 2012 at 05:09:16PM +0000, Simon Riggs wrote:
>> Attached patch makes SnapshotNow into an MVCC snapshot, initialised at
>> the start of each scan iff SnapshotNow is passed as the scan's
>> snapshot. It's fairly brief but seems to do the trick.
>
> That's a neat trick.  However, if you start a new SnapshotNow scan while one is
> ongoing, the primordial scan's snapshot will change mid-stream.

Do we ever do that? (and if so, Why?!? or perhaps just Where?)

We can use more complex code if required, but we'll be adding
complexity and code into the main path that I'd like to avoid.

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