On Tue, Mar 3, 2015 at 9:24 AM, Andres Freund <and...@2ndquadrant.com> wrote: > On 2015-03-03 08:59:30 +0900, Michael Paquier wrote: >> Already mentioned upthread, but I agree with Fujii-san here: adding >> information related to the state of a block image in >> XLogRecordBlockHeader makes little sense because we are not sure to >> have a block image, perhaps there is only data associated to it, and >> that we should control that exclusively in XLogRecordBlockImageHeader >> and let the block ID alone for now. > > This argument doesn't make much sense to me. The flag byte could very > well indicate 'block reference without image following' vs 'block > reference with data + hole following' vs 'block reference with > compressed data following'.
Information about the state of a block is decoupled with its existence, aka in the block header, we should control if: - record has data - record has a block And in the block image header, we control if the block is: - compressed or not - has a hole or not. Are you willing to sacrifice bytes in the block header to control if a block is compressed or has a hole even if the block has only data but no image? -- Michael -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
