Re: LSN as a recovery target

On Mon, Sep 5, 2016 at 4:02 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On 5 September 2016 at 06:55, Michael Paquier <michael(dot)paquier(at)gmail(dot)com> wrote:
>> On Sun, Sep 4, 2016 at 11:30 PM, Simon Riggs <simon(at)2ndquadrant(dot)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.

Looks good to me. Thanks for the wordsmithing.
--
Michael