On Thu, Oct 27, 2011 at 6:25 PM, Fujii Masao <masao.fu...@gmail.com> wrote: > On Thu, Oct 27, 2011 at 5:18 PM, Magnus Hagander <mag...@hagander.net> wrote: >> Not sure I follow. When we arrive at PQgetCopyData() there should be >> nothing buffered, and if the end of stream happens there it returns >> -1, and we exit, no? So where is the data that's lost? >> >> I do realize we don't actually fsync() and close() in this case - is >> that what you are referring to? But the data should already have been >> write()d, so it should still be there, no? > > Oh, right. Hmm.. xlogdump might be the cause. > > Though I've not read the code of xlogdump, I wonder if it gives up > outputting the contents of WAL file when it finds a partial WAL page... > This strikes me that recovery code has the same problem. No? > IOW, when a partial WAL page is found during recovery, I'm afraid > that page would not be replayed though it contains valid data.
My concern was right. When I performed a recovery using the streamed WAL files, the loss of data happened. A partial WAL page was not replayed. To avoid this problem, I think that we should change pg_receivexlog so that it writes WAL data *by the block*, or creates, like walreceiver, WAL file before writing any data. Otherwise, though pg_receivexlog streams WAL data in realtime, the latest WAL data might not be available for recovery. 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
