Re: LSN as a recovery target

On 5 September 2016 at 06:55, Michael Paquier <michael.paquier@gmail.com> wrote:
> On Sun, Sep 4, 2016 at 11:30 PM, Simon Riggs <simon@2ndquadrant.com> wrote:

>> I noticed we don't mention what LSN is anywhere, so I'd like to apply
>> the following doc patch also.
>
> +1 for the idea. What do you think about adding a mention to the
> system data type pg_lsn?
>
>    <para>
> +   <acronym>WAL</acronym> records are appended to the <acronym>WAL</acronym>
> +   logs as each new record is written. The insert position is described by
> +   a Log Sequence Number (<acronym>LSN</acronym>) that is a byte offset into
> +   the logs, increasing monotonically with each new record. Two
> +   <acronym>LSN</acronym>s can be compared to calculate the volume of
> +   <acronym>WAL</acronym> data that separates them, so are used to measure
> +   progress of <acronym>WAL</acronym> during replication and recovery.
> +  </para>
> Here we could for example append a sentence like "The system data type
> <link linkend="datatype-pg-lsn"><type>pg_lsn</></link> is an internal
> representation of the LSN".

Good input, thanks. v2 attached.

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