Обсуждение: pgsql: Change how first WAL segment on new timeline after promotion is
Change how first WAL segment on new timeline after promotion is created. Two changes: 1. When copying a WAL segment from old timeline to create the first segment on the new timeline, only copy up to the point where the timeline switch happens, and zero-fill the rest. This avoids corner cases where we might think that the copied WAL from the previous timeline belong to the new timeline. 2. If the timeline switch happens at a segment boundary, don't copy the whole old segment to the new timeline. It's pointless, because it's 100% identical to the old segment. Branch ------ master Details ------- http://git.postgresql.org/pg/commitdiff/ba94518aad23beb800b657bd0cc8c4e7ea43ca33 Modified Files -------------- src/backend/access/transam/xlog.c | 82 +++++++++++++++++++++++++++---------- 1 file changed, 61 insertions(+), 21 deletions(-)
Hi Heikki, While writing a test script for http://archives.postgresql.org/message-id/20141205002854.GE21964%40awork2.anarazel.de I noticed that this commit broke starting a pg_basebackup -X * without a recovery.conf present. Which might not be the best idea, but imo is a perfectly valid thing to do. To me the changes to StartupXLOG() in that commit look a bit bogus. The new startLogSegNo is initialized to XLByteToSeg(EndOfLog)? Which points to the end of the record +1? Which thus isn't guaranteed to exist as a segment (e.g. never if the last record was a XLOG_SWITCH). Did you perhaps intend to use XLogFileInit(use_existing = true) instead of XLogFileOpen()? That works for me. I've attached my preliminary testscript (note it's really not that interesting at this point) that reliably reproduces the problem for me. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services