On Wed, Feb 17, 2010 at 3:27 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Magnus Hagander <mag...@hagander.net> writes: >> On Wed, Feb 17, 2010 at 06:55, Fujii Masao <masao.fu...@gmail.com> wrote: >>> 2. Straightforwardly observe the alignment rule. Since the received WAL >>> data might start at the middle of WAL block, walreceiver needs to keep >>> the last half-written WAL block for alignment. OTOH since the received >>> data might end at the middle of WAL block, walreceiver needs zero-padding. >>> As a result, walreceiver writes the set of the last WAL block, received >>> data and zero-padding. > >> May there be other reasons to d this as well? > > Writing misaligned data is certain to be expensive even when it works...
Yeah, right. After I remove O_DIRECT, I'll change walreceiver so as to do an alignment correctly, and then I'll test the performance. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
