Re: [REVIEW] Re: Compression of full-page-writes

On Sun, Dec 14, 2014 at 5:45 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 13 December 2014 at 14:36, Michael Paquier <michael.paquier@gmail.com> wrote:
>
>> Something to be aware of btw is that this patch introduces an
>> additional 8 bytes per block image in WAL as it contains additional
>> information to control the compression. In this case this is the
>> uint16 compress_len present in XLogRecordBlockImageHeader.
>
> So we add 8 bytes to all FPWs, or only for compressed FPWs?
In this case that was all. We could still use xl_info to put a flag
telling that blocks are compressed, but it feels more consistent to
have a way to identify if a block is compressed inside its own header.
-- 
Michael