[COMMITTERS] Convert OID intergers to path strings.

Hi, committers! I am naive for postgresql. I have millions of tiny databases. When I was trying to createdb, it fails because each database is saved in $PG_DATA/base/Oid. In UFS system, one directory maximum can hold 32768 subdirectories. Oid is 4 byte integer. Subdirectory is a path name with m

[COMMITTERS] Can not create more than 32766 databases in ufs file system.

Hi, pgsql-committers! I cannot created more than 32766 databases with freeBSD in one setup, not as the document says, "as many as you like". I found the problem is that the directory pgsql/data/base cannot hold more than 32766 subdirectories. I suggest to make 32766 subdirectories in base director