Log Message:
-----------
Modify MoveOfflineLogs/InstallXLogFileSegment to avoid O(N^2) behavior
when recycling a large number of xlog segments during checkpoint.
The former behavior searched from the same start point each time,
requiring O(checkpoint_segments^2) stat() calls to relocate all the
segments. Instead keep track of where we stopped last time through.
Modified Files:
--------------
pgsql/src/backend/access/transam:
xlog.c (r1.184 -> r1.185)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c.diff?r1=1.184&r2=1.185)