On 28 May 2014 15:34, Fujii Masao <masao.fujii@gmail.com> wrote:
>> Also, compress_backup_block GUC needs to be merged with full_page_writes.
>
> Basically I agree with you because I don't want to add new GUC very similar to
> the existing one.
>
> But could you imagine the case where full_page_writes = off. Even in this case,
> FPW is forcibly written only during base backup. Such FPW also should be
> compressed? Which compression algorithm should be used? If we want to
> choose the algorithm for such FPW, we would not be able to merge those two
> GUCs. IMO it's OK to always use the best compression algorithm for such FPW
> and merge them, though.
I'd prefer a new name altogether
torn_page_protection = 'full_page_writes'
torn_page_protection = 'compressed_full_page_writes'
torn_page_protection = 'none'
this allows us to add new techniques later like
torn_page_protection = 'background_FPWs'
or
torn_page_protection = 'double_buffering'
when/if we add those new techniques
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
