| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Dan Scales <scales(at)vmware(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Noah Misch <noah(at)leadboat(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, david(at)fetter(dot)org, aidan(at)highrise(dot)ca, stark(at)mit(dot)edu, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: 16-bit page checksums for 9.2 |
| Date: | 2012-01-28 20:44:32 |
| Message-ID: | 4F245E30.20704@enterprisedb.com |
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| Lists: | pgsql-hackers |
On 28.01.2012 15:49, Simon Riggs wrote:
> On Fri, Jan 27, 2012 at 9:07 PM, Dan Scales<scales(at)vmware(dot)com> wrote:
>
>> Also, I missed this before: don't you want to add the checksum calculation (PageSetVerificationInfo) to mdextend() (or preferably smgrextend()) as well? Otherwise, you won't be checksumming a bunch of the new pages.
>
> You don't need to checksum the extend because no data is written at
> that point.
That's not correct. smgrextend writes a block of data just like
smgrwrite does. When a relation is extended by the buffer manager, it
calls smgrextend with an all-zeros block, but not all callers do that.
See rewriteheap.c and nbtsort.c for counter-examples.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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