Re: Freezing is not WAL-logged - Mailing list pgsql-bugs

From Heikki Linnakangas
Subject Re: Freezing is not WAL-logged
Date
Msg-id 45388DAB.1060608@enterprisedb.com
Whole thread Raw
In response to Re: Freezing is not WAL-logged  (Alvaro Herrera <alvherre@commandprompt.com>)
Responses Re: Freezing is not WAL-logged  (Alvaro Herrera <alvherre@commandprompt.com>)
Re: Freezing is not WAL-logged  ("Jim C. Nasby" <jim@nasby.net>)
List pgsql-bugs
Alvaro Herrera wrote:
> Tom Lane wrote:
>> "Heikki Linnakangas" <heikki@enterprisedb.com> writes:
>>> I just noticed that freezing a tuple (in vacuumlazy.c) is not
>>> WAL-logged.
>> The theory is that this doesn't matter because the tuple is committed
>> either way ... it's equivalent to a hint-bit update which we don'ton
>> WAL-log either.
>
> Also it'd be hugely expensive to log each freeze operation.  The
> alternative would be to log a VACUUM FREEZE, but that has the potential
> to cause enormous recovery runtime.

Freezing isn't very common, and a single WAL record per page would be
enough. I can write the patch.

It does have the potential to increase recovery times, but I don't think
we can just cross our fingers and hope that no crash happens after
freezing some tuples.

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

pgsql-bugs by date:

Previous
From: Peter Eisentraut
Date:
Subject: Re: BUG #2698: Update table alias not supported
Next
From: Alvaro Herrera
Date:
Subject: Re: Freezing is not WAL-logged