Prevent WAL logging when COPY is done in the same transation that

doc/src/sgml/perform.sgml

src/backend/access/heap/heapam.c

src/backend/access/heap/tuptoaster.c

src/backend/catalog/index.c

src/backend/commands/copy.c

src/backend/executor/execMain.c

src/backend/utils/cache/relcache.c

src/include/access/heapam.h

src/include/access/tuptoaster.h

src/include/utils/rel.h