Transaction log manager core code.

src/backend/access/transam/Makefile

src/backend/access/transam/rmgr.c

src/backend/access/transam/xlog.c

src/backend/postmaster/postmaster.c

src/backend/storage/file/fd.c

src/backend/tcop/utility.c

src/include/access/rmgr.h

src/include/access/xlog.h

src/include/storage/proc.h

src/include/utils/elog.h