Re: [PATCH]make pg_rewind to not copy useless WAL files

On Sat, Sep 30, 2017 at 8:18 PM, chenhj <chjischj(at)163(dot)com> wrote:

> On 2017-09-30 02:17:54，"Alexander Korotkov" <a(dot)korotkov(at)postgrespro(dot)ru>
> wrote:
>
>
> Great. Now code of this patch looks good for me.
> However, we forgot about documentation.
>
> <para>
>> The result is equivalent to replacing the target data directory with
>> the
>> source one. Only changed blocks from relation files are copied;
>> all other files are copied in full, including configuration files. The
>> advantage of <application>pg_rewind</> over taking a new base backup,
>> or
>> tools like <application>rsync</>, is that <application>pg_rewind</>
>> does
>> not require reading through unchanged blocks in the cluster. This makes
>> it a lot faster when the database is large and only a small
>> fraction of blocks differ between the clusters.
>> </para>
>
>
> At least, this paragraph need to be adjusted, because it states whose
> files are copied. And probably latter paragraphs whose state about WAL
> files.
>
>
>
> Your are rigth.
> I wrote a draft as following, but i'm afraid whether the english statement
> is accurate.
>

I'm not native english speaker too :(

Only the WAL files between the point of divergence and the current WAL
> insert location of the source server are copied, *for* other WAL files are
> useless for the target server.

I'm not sure about this usage of word *for*. For me, it probably should be
just removed. Rest of changes looks good for me. Please, integrate them
into the patch.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company