On 06/13/2014 10:14 AM, Michael Paquier wrote:
On Mon, Jun 2, 2014 at 9:55 PM, Michael Paquier
<michael.paqu...@gmail.com> wrote:
On Wed, Apr 23, 2014 at 9:43 PM, Heikki Linnakangas
<hlinnakan...@vmware.com> wrote:
Perhaps there are parts of what is proposed here that could be made
more generalized, like the masking functions. So do not hesitate if
you have any opinion on the matter.
OK, attached is the result of this hacking:

Buffer capture facility: check WAL replay consistency

It is a tool aimed to be used by developers and buildfarm machines
that can be used to check for consistency at page level when replaying
WAL files among several nodes of a cluster (generally master and
standby node).

This facility is made of two parts:
- A server part, where all the changes happening at page level are
captured and inserted in a file called buffer_captures located at the
root of PGDATA. Each buffer entry is masked to make the comparison
across node consistent (flags like hint bits for example) and then
each buffer is captured is with the following format as a single line
of the output file:
LSN: %08X/%08X page: PAGE_IN_HEXA
Hexadecimal format makes it easier to detect differences between
pages, and format is chosen to facilitate comparison between buffer
- A client part, located in contrib/buffer_capture_cmp, that can be
used to compare buffer captures between nodes.

Oh, you moved the masking code from the client tool to the backend. Why? When debugging, it's useful to have the genuine, non-masked page image available.

- Heikki

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