Re: Scaling up deferred unique checks and the after trigger queue

From: Dean Rasheed <dean(dot)a(dot)rasheed(at)googlemail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Scaling up deferred unique checks and the after trigger queue
Date: 2009-10-19 17:07:40
Message-ID: 8e2dbb700910191007u3bd1d763w94c8960add24f728@mail.gmail.com
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2009/10/19 Robert Haas <robertmhaas(at)gmail(dot)com>:
> On Mon, Oct 19, 2009 at 12:48 PM, Dean Rasheed
> <dean(dot)a(dot)rasheed(at)googlemail(dot)com> wrote:
>> This is a WIP patch to replace the after-trigger queues with TID bitmaps
>> to prevent them from using excessive amounts of memory. Each round of
>> trigger executions is a modified bitmap heap scan.
>
> If the bitmap becomes lossy, how do you preserve the correct semantics?
>
> ...Robert
>

The idea is that it filters by the transaction ID and command ID of
modified rows to see what's been updated in the command(s) the trigger
is for...

- Dean

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